I have used a Brunton Solar Roll 14 one summer, and with absolutely terrible results. It was sold on ebay the following fall. I bought that panel for it's 12 volt capability to charge a few camera items that at the time could only be charged with this rather large panel (14 watts allegedly, $400 list price).
In testing and perfect conditions, it took 8 hours and perfect panel positioning to charge two AA batteries. It never charged anything while strapped to the backpack, and we could not just sit around for hours during the middle of the day to bump the batteries up a few amps.
following that rather disappointing first experience, I have not used any solar chargers. Instead I used AA Lithium batteries or simply additional camera batteries, which are cheap and more reliable than my then experience with solar charging.
Since then, companies like Goal Zero have appeared and the the efficiency of solar chargers has improved significantly. Lots of testimony has been shared of successful charging while on the trail. So now I am again considering to bring a panel to charge a Go Pro along the way this season, as well as to serve as a booster for my sat phone and DSLR batteries.
The Goal Zero Nomad 7 Plus
is probably one of the most efficient panels on the market right now that is aimed at the smaller devices most people bring along on the trail, and combined with a now available upconverter camera battery charger (turning USB to higher voltage), I can use the power bank to charge my 8.4 volt DSLR batteries. If the panel can really charge a 5000mAh bank in 1-2 days on the back of my pack, I am looking at quite some weight savings overall.
For now, I am still doing research on this, but theoretically I should be able to lose one sat phone battery and at least one DSL battery from my pack, which is more than half the weight of the panel itself. It is small enough to mount in top of my pack where sunlight will reach it even while southbound.
A small power bank stick (under 6000 mAh) to plug into the panel at all times while on top of my pack would complete the setup. Cost is also better than back in 2008 when I first tried this. I'll keep the GPS on Lithium AAs, as it just eats those batteries, plus those AAs are super light and also work in my camera's grip.
As for battery life and recharge cycles - that's totally normal or most rechargeable batteries except maybe lead acid batteries. Not something I'd care about, as all the batteries I am recharging are actually rather cheap to replace.
If I decide to buy the Goal Zero Nomad 7 Plus (Plus is important - it is far better and lighter than the older Nomad 7 that's just $20 cheaper), expect a report in late July and perhaps a prelim report in a few weeks, as I will obviously want to test it in simulated trail conditions before committing to it.
Actually, just did some more searching, and there is a quite affordable competitor to the Nomad 7 Pro from Anker. Gets top review at Outdoorgearlab.com, and costs less than half. I am a sucker for a good deal and I think I will grab that Anker charger for this trip. http://www.outdoorgearlab.com/Solar-Charger-Reviews