I virtually never plug mine in and rotate a real Nokia battery with two cheap eBay Hong Kong batteries. I have been doing this for almost a year and haven't noticed any significant dropoff, though I imagine there has been some. I bought a $10 battery charger from eBay as well, and that's what I use for the charging.

I think that more than one battery + a charger is the way to go. Then you don't care how long it takes to charge. And if one of the batteries starts getting weak, I'll just buy another one.