Well, I have a second generation Nitecore two bay charger, and the spring/slides are fairly tight but have done no damage to my mod once I started being very careful about insertion. What I do is when charging, pull the slides ALL the way down, place my batteries gently in the housing, and then slooowllly release until they're resting on the bottom of the battery. I believe there was a post a while back about the amount of pressure different slides put on chargers, but I can't remember the name of the thread. Mine's not terrible, it won't put dents in the bottom part of the battery via charging, though some people have chargers that do that. To take them out, I gently slide them sort of sideways, while keeping one hand on the spring loaded slide, so it doesn't freak out....
With that said, I had an IPV-5 with a "ribbon" and I have to say, I think most of my wrap degradation came from that, even with the ribbon, as I had to basically "pop" them out, and they were a tight fit. I've only used new batteries in the steampunk, and while the battery door could use some work, I do like the design, where you just slide them in there, and I've had 2 married pairs of batteries for going on 2 months without the slightest hint of damage, and the battery door is easily taken care of by the silicone sleeve I got to keep it in place. I'm fairly convinced that most of my battery degredation early on was caused by my mod, and by not being SUPER careful with the charger, but I've got 2 sets of batteries that are in perfect condition after two months, so I do think the design of the mod plays a role. With all that said, rewrapping is easy to do, and inexpensive. IMRbatteries even sent two free wraps with my last order (now I will have 10 "new" pairs, and my goal is to rewrap as little as possible, while still having "safe" batteries.
Anna