Meridian DPS 7000 ? 5200? are these speakers actually worth having as a long term deal...

7200 vs 5200 differences are quite large. Not only in physical size but also in amplifier power, number of drivers etc. In terms of sound the 7200 is capaple of higher SPL, lower bass, and better dynamics. All in all the 7200 is in my opinion Meridian's best all around speaker. The 7200.2 even more so with updated electronics and new tweeters. When you go to the SE variant it is even more so.

CMB, are the older 7200s updgradable?

Yes, all DSP7200 speakers can be upgraded.

" Are any of the DSP Meridians worth looking into. DSP 5200 or DSP 7000 would be of interest."

If you're used to Wilson's with good electronics, there's no way you'll settle for a pair of 7000's. Meridian is way over priced for the level of sound quality they deliver. I wanted to try home theater so I went out and bought a Meridian system. Here's my review: They look nice, they're well made and they play extremely loud. 

I've always been a 2 ch person, so I evaluated the speakers setup for both theater and music. Aside from the high price, they're OK for theater. For music, they just can't compete. For comparison, I took a pair of Vandersteen 2's, an Ayre amp and a Wadia CD player, and put them right next to the Meridians. With the exception of volume and bass, the 7000's were embarrassed by the Vandersteen's. And so were the 8000's, for that matter. The 7000's were my surrounds, and I had 3 8000's in the front. Also, plan on buying some expensive cables. Given that Meridian puts both a dac and amps inside the speakers, power cords make a huge difference. Consider them a must buy. The Shunyata's gave the best results, and they were 2k each.

I don't have the time to keep going on here. If I missed something or you have a question, post, and I'll do my best to give you an answer.  

BUMP, ouch.
 Just for perspective, I don't get vandersteen speakers or their appeal, maybe if you listen to Annie lennox all night they're great, but i'm not surprised the thread died after that comparison. 
I'm sure the op has moved on by now, but there's several dsp's listed on ag right now and I would like to give my review and i'll compare them to the revel salon 2's I owned that I used a Hegel h360 to drive them with. 
Dsp8000sl listed on ag for $16k I struck a deal and bought. Bass, pitch, definition, depth and detail the 8k's have it case closed. the salon 2 in my room couldn't deliver and since much of reproduction rely's on the bass/room lock sound staging also suffered with the salon's in comparison to the 8k's. 
Loudness? lol the 8k can reach 118-120 db. imaging? The salon2 is really impressive and manages to walk that line between detail and musicality better than the 8k even since I upgraded the 8k to special edition with new electronics and a be tweeter the salon 2 still sets the bar for plucking the smallest details and placing them in their own space. The 8k puts me at the venue making music more involving and a more forward mid range is a positive to me but might be a knock to another. Both speakers can be held in the same company, but in my room with my little H360 the 8k dismantled the salon2 in all but pin point imaging, example Peter Gabriel mercy street the overlayed vocals the salon gave just a little more space between vocals same with 'Midnight train to Georgia", just that little bit more space between the pips. For the money I spent upgrading the 8k to 'SE' I could have sold the Hegel and bought ANY components here used to get the very best out of them. I preferred the presentation of the meridian in my room with more recordings and I didn't have to deal with bass nulls at the listening spot conventional boxes can produce (no subs needed). I know the writing's all over the place but it's a forum not publication.