Some thoughts:

life of batteries: Number of cycles is not an issue for most. How many times do you fly in a year? Even if 50 times (I wish!) it would take 4 years to use up the 200 cycles life of a lead-acid battery, and by then it would deteriorate anyway due to time alone. Even the Lithium battery is going to die after a decade or so, thus will never even get close to the promised 2000 cycles.

capacity: in my case, I find that a small 4 or 5 AH battery suffices, even for a 6-hour flight. OK, I don't have FLARM nor a transponder. And my computer is a Nook e-reader, drawing about 1/4 amp. YMMV.

cost: I considered a LiFePo battery last year when I needed to replace my SLA battery (again), but found that they are still about $150, and I got _three_ new small (4 or 5 AH) SLAs for a total of $27 including the shipping (from Apex). The weight of such is similar to the weight of a (larger) LiFePo battery, and for my needs, the capacity is sufficient (see above). A larger SLA is not expensive either, but does add a few pounds.

solar panel in glider: don't think of it as a charger for the battery. Rather, is helps supply the ongoing current to the always-on (while flying) gizmos, reducing the load on the battery (possibly to zero when you are not talking on the radio). You do need something that will prevent overcharge if the glider sits in the sun a while, but a charge controller designed for SLA is fine for that. Worry about fully recharging the battery only when you take it home. (Unless you want to avoid having to take it home.)

A 10-watt solar panel is fairly large, presumably it's the flexible type, glued onto the outside of the glider? I've considered adding a smaller panel inside the cockpit, presumably on the glare shield above the instruments, but doing the math convinced me that it's not worth the trouble, as it would only stretch the battery capacity a modest amount. It's easier to just get a larger battery. (Also, a panel on the glare shield may reflect sunshine into the pilot's eyes, directly, or reflected again via the canopy.)