I have the Lacrosse charger and your can refresh with it I don't know if it does any good or not. The best thing is to buy good batts to start with. The ebay no name batts are 50/50 if you are getting what you pay for. I have been using the Duracell green and black (AA 2350 I think) and they seem to be very good. I use them in my flash units for my cameras and they seem to be about the best I have found. I also use them in my gre500 and maybe slip in energizers if the good green batts are all dead. Both seem to work good. I get way over 4 hours but it does depend on if you have a lot traffic and have the speaker turned up.
With my charger I write on the batt what it charged at the first time and the date of first charge, that way I know if a batt has shot craps and needs to be crap canned. I have also found that if the batts fully discharge the Lacrosse doesn't like it and won't charge the batt, this seems to be a AAA deal but I have other chargers that I can use to put a small charge into the batt then stick it on the other charger to fill it up.
Also don't buy those precharged batts they are lower power for some reason and they want to charge you 2x for them being charged what a rip off.