SL-1200G/Hana ML Best Headshell

Should have noted that when you multiply effective mass times compliance and take the square root, keeping compliance constant, then the ratio of the result with a 9g vs 12g effective mass is even less different than the square roots of the two numbers 12 and 9 would suggest.

As regards the SL1200G or GR tonearm(s), if the headshell weighs 7.6g, which is light as headshells go, then the total effective mass of the tonearm in question would very likely be greater than 9g, it seems to me. More like 12g.

Think of it this way: square root of 9 is 3. Square root of 12 is ~3.4. So the difference between 9g and 12g is not going to affect the calculation of Fr by much.

If you look at the math, there is really quite a bit of leeway in effective mass and compliance that will give you a resonant frequency that falls within the typical range of 8 to 12Hz.  And anyone who has done vinyl for a long time with a variety of cartridges and tonearms will tell you that you can get away with a slightly lower lower limit (lower than 8Hz, that is).  The first reason is that the Fr is dependent upon the square root of the effective mass times the compliance.  Taking the square root has the effect of blunting differences.  (To understand what I mean, go on line and use one of the Fr calculators.  Plug in some extreme values for M and C and note how relatively little that affects the results.)  The second reason is that one really does not know and cannot easily know true accurate values for M and C for YOUR tonearm and YOUR cartridge, unless you empirically determine C and go through an arduous calculation for M, instead of using numbers given to us by the various manufacturers, which are average values at best. (I don't think every cartridge X has exactly the compliance that its manufacturer tells us it has, even out of the box, but especially if it is vintage or well used.) So, in the end, "just try it" is a good rule of thumb. 

Don’t bother. The titanium headshell is probably too heavy, if it really weighs 19 g or more. I’m not sure you would benefit even from changing the original headshell, but if you feel like experimenting, I would go with the carbon fiber headshell largely because of lower weight. You realize probably that a spec about the weight of the cartridge that the tonearm can handle does not tell you anything about the effective mass of the tonearm. Anyway, I am sure you’ll be just fine with either the stock head shell or a carbon fiber headshell.