It's probably worth noting that all recharagable batteries eventually reach a point where recharging isn't possible. This is true regardless of whether the batteries are lithium ion or regular nicad.
The manufacturer of the rechargeable AA nicad batteries I use in my Sea & Sea and Nikonos strobes predicts that their batteries can be recharged 2100+ times. Personally, I think that's a bit optomistic. But, I'll be happy if their prediction is correct. Reduced battery life is the primary reason that I trade in my cell phone every few years for a new one. It's also the reason I've got a couple of old notebook computers stashed in a closet. The computers work when plugged in, but the batteries are dead.
Eventually, I will have to replace my long-lived Ikelite DS161 battery packs. I wouldn't let the Ikelite lithium ion battery packs be a deal killer. This is especially true if the strobes and lithium ion battery packs are working.
My monthly maintenance routine on my Ikelite strobes and battery packs includes exercising the strobe capacitors and putting a fresh charge on the battery packs. Both parts of this routine are easy.
Exercising the capacitors requires hooking the strobes to a camera via a housing, firing the strobes and allowing the strobes to recycle. Like rechargable batteries, capacitors can deteriorate with age and stop working it left sitting for prolonged periods of time.
Putting a fresh charge on the Ikelite battery packs involves draining the batteries by placing the assembled DS161 in a bucket of ice water, turning the strobe's video light on and leaving it on until a check of the power indicator lights show that the strobe is low on power. For me, if all of the power indicator lights are off, it's time to recharge the battery. I do not discharge battery power until the video light stops working.
If you decide not to purchase those DS161 strobes, please drop me a PM. I may know some people who are looking for a good deal on some used DS161 strobes.
-Tinman