Well first it depends on what the glasses have to work with. If the display bleeds horribly far into the next frame, then good glasses can only do so much.
Beyond that the statistics that matter are:
1) How much light do the glasses block when fully closed, and do they block all colors evenly
2) How long do the glasses take to fully close and open
3) Do the glasses support a duty cycle.
4) Can you adjust the duty cycle/phase either from the glasses (maybe the X104s will have this) or through a companion emitter (so far, only the Bitcauldron/Zigbee based IR-to-RF units from Monster or VesaSync-to-RF units from other vendors -- you cannot buy direct from BitCauldron apparently.)
But good luck getting any information on 1) 2) or 3) out of the vendors, and I have not seen any consumer reviews that actually measure these things with any degree of professionalism.
Not every brand of glasses that claim to support your Panasonic will even support a duty cycle, even though the Panasonic IR protocol does support duty cycle. Some will just fake it. Heck, not every pair of glasses that claim to support your Panasonic will ven sync to your particular set.
Nor is it a safe assumption that the Panasonic will send the right duty cycle out. It's not even a safe assumption that a TV will continue to send the right IR signal after a firmware upgrade, as we saw with Samsung. You can't even really assume safely that the glasses recommended and sold by your TV set manufacturer are truly optimized to your set.
I would recommend the BitCauldron stuff just based on being able to tune it yourself, but I cannot, because I do not know the quality of the lenses/response time and have not been able to try a set out myself.
Now theoretically, if the lenses perform well and if you can adjust the duty cycle and phase, you should be able to find a clean strip of image inside each frame, but if the size of the clean strip is too small, you'll have to crank the set up really hard because the glasses will be pretty black, and you might start to notice flicker. At least you'll have the choice to make that trade-off, however.
In short it's a treacherous marketplace right now, so only buy from vendors with a liberal return policy, and expect to spend some time finding the right model for your set.