Prob should add the Bantam BC8DX - its another true dual charger. Another that will allow dual batt charging is the iCharger 208B.

The DUO3 is basically two complete chargers and balancers in a single housing - its expensive as is the Bantam BC8DX. I wouldn't place the Racer's Edge in the same league as its only a 50watt charger and is not a dual charger. You need a lot of charger output power to go the dual route, like the 360watts from the Duo3, 320watts from the Bc8DX, or 350watts from the 208B.

The thunder and skycharger (and oithers) are clones coming from either China or Asia where labor costs are cheap. If you're only going to be doing 2S lipo, you could buy 2 50watt chargers and a single power supply with enough power to run both chargers an spend a lot less that any of teh true dual chargers. They will all do lipo NiMh, NiCd and LiFe. Some will and some won't handle li-ion, but thats never really succeded in RC anyway.