Martin logan CLS II Vs Magnepan 1.7

I'll say it once more: ONE sub, properly placed between them (and set to 90 deg. phase angle, 80Hz or lower xovr.) provides the MOST seamless performance with panel speakers. Maggies or ML; large room or small. If you haven't tried it, you're in store for a very pleasant surprise ;--)

Electrodynamic vs. electrostatic sonics is a matter of personal preference -- I've owned both.
.

Keep the Logans -- you already love them for all the right reasons; and Maggies can never replicate the accuracy of an electrostat. Get a single ML Depth subwoofer and stick it right in the middle of the panels (see my system) and you'll have the best of all worlds.

Do not get two Depths! The panels radiate front and back, at 180 degrees out of phase; so a single, omnidirectional sub in the center, does a much better job phase-matching to the panels, than two subs ever can (i.e., the sub disappears.) If your room happens to be larger than say 18 x 25, you'll probably need the (larger) Descent subwoofer in order to listen to rock at a more realistic level ;--) You should also consider (again, if you have a larger room) replacing the panels with the new version as I just did, especially if yours are over 20 yrs old (like mine.) The new ones have a more robust diaphragm and a slightly higher power handling capacity. However, if your room is 'normal' size, replacing the panels is optional if the old ones are working OK. And ML now says they plan to always have replacements available in the future (although they were originally $800/pr, now $1500!)

The Depth vs. the Descent? Having smaller, lighter woofers, the Depth has very fast response, and excels at producing bass transients which is as you say, what you want for great rock (and I agree.) However, if you need more bass output to fill a larger room, DO NOT use two Depths! Go to a single Descent instead, because the phase-matching benefits of a single sub still outweigh the (slightly) better transients you'll get with the Depth.

You can get a used Depth on AgoN for under $1K. I've also been told (by someone who knows;--) that the original Depth and Descent models have better performance, and almost no reliability issues, compared to the "i" models.

Yeah, hang on to those CLS's!
.

Well, I just think this conversation has no basis in reality. Planar magnetic vs. electrostatic is simply apples to oranges -- and so are their native sonics! Like I already advised the OP, "Keep the Logans -- you already love them for all the right reasons; and Maggies can never replicate the accuracy of an electrostat."

There are a few 'wherefores' and 'notwithstandings' in connection with both of these speakers, however, and if they were not being observed by those above who recounted their personal experiences, then I don't put much stock in those experiences -- sorry, but here, for instance, is a typical 'whereas':
If you aren't running an electrostat (ANY electrostat) with a decent, conventional tube amp (conventional, meaning with output transformers!) then I don't care what you think about their sound because you've never really HEARD them!
WHEREAS
If you aren't running your planar magnetic with the BEST (most refined) solid state amp you can afford (afford = minimum six figures these days), or a great refined used ss, like a Levinson 23.5, then I don't care what you think about THEIR sound because you've never really HEARD them either! And in the case of planar magnetics, you will absolutely NEVER enjoy them (regardless of amp) unless most of your listening is at, or just below, performance levels. This is because their membranes are heavy (compared to stats) and so their ability to move air (versus input power) falls sharply at a certain point; not gradually, like cone drivers and most stats.

Other observations:

Electrostats simply DON'T DO BASS!! So get over it. Deploy a single sub as I described, and you'll never even know it's there -- but it HAS to radiate omnidirectionally, like the Logan subs, or any downward-firing sub.

There is nothing like the accurate sound of panel/dipole bass (Maggies that is, not Logans ;--)) or dipole cones mounted (face-to-face) on an infinite baffle (basically the same thing as 'panel bass')
HOWEVER
even Maggies can't be all-they-can-be basswise, if you're unwilling to go to the trouble of bi-amping them. Otherwise get a sub and deploy it as with stats.

Speaker cables are another MAJOR issue in the Maggie v. Logan discussion:
*Electrostats are a capacitive load.
You CAN NOT use CARDAS or other MULTI-STRANDED cable! They have something like 400 to 500 picofarads per foot. If you use them, you're in for a mush-fest! You need something under 20 ppf/foot; under 16 is better! Solid core is always a good bet. Purist Proteus Provectus, Speltz AntiCables, or the (now discontinued) Vitual Dynamics models. These all have ultra-low capacitance because they a.) have solid core conductors and b.) have separated + and -- runs. Speaker cables for electrostats should also have a certain amount of resistance (yes, resistance!) according to Roger Sanders, and he ought to know!

*Maggies are an inductive load.
Cables with low inductance are preferable. Flat cables (like NoDoze) are naturally low inductance. So are any cables with separated runs (again, like AntiCables or Purist Provectus or many of the Virtual Dynamics models). And keep them off carpeted floors. If you use cables with high inductance characteristics, prepare to be scratching your head and wondering why you spent all that money ;~))

Don't know the specs of your cables? CALL THE DAMN MANUFACTURER UP AND ASK THEM! It's your money; and if he/she can't/won't tell you, then demand your money back -- including return shipping! I'm serious, I actually threatened one manufacturer (whose products I actually like quite a lot) but I wasn't kidding, and I had an answer a day later!

Bottom line, in my opinion, is that there are just too many variables that (differently) affect the optimum performance of each one of these two designs. Yes you CAN have a discussion about them, of the "compare and contrast" variety, but unless you are willing to experience them, or are sure you HAVE experienced them each, under the optimal conditions for each, then nothing you THINK YOU KNOW is probably going to be very relevant to a discussion like this.
.

Better my book than someone else's ;~))