[MetalMan]

Sorry I didn't get my input in sooner, but here are my answers:

1. 4.2v won't cause damage, but it could reduce the cycle life rather dramatically. And if you do charge to 4.2v, a higher charge rate should be utilized, and you should end the charge shortly after it enters the CV phase. This will help keep the cells in better shape.

2. You can charge A123 cells as fast as you want. If you had the appropriate charger you could do a 12C charge (5mins). The TP-1010C will charge A123s properly when you have the updated software.

3. Some Lipo balancers won't balance below a certain voltage. In the case of the TP balancers, they will balance A123 cells, but they won't do it all that precisely (which is fine, since these cells don't really need to be balanced much at all).

4. The sleeves that the cells are in are good. If the cells are dropped, they can absorb a portion of the energy of the fall to keep the cells from denting as badly. You could use shrink wrap, but the cardboard is better IMO :).

I'm running 5s2p A123 in my Revo (zeropointbug is also running 5s2p in his E-Maxx). 5s2p is an excellent setup - good charge times (I charge at 8.30A using my "hacked" Astroflight 109), strong power right until it dumps (and it dumps HARD), 15min. runtimes, excellent safety, and super low cost (this pack cost less than $120 after building materials expenses).

Balancing with A123 cells isn't really all that necessary. These cells can tolerate overcharge/overdischarge quite well. With Lipos, good balance is critical since bad balance can lead to overcharged/overdischarged cells, and Lipos are much more sensitive than A123 cells. The first 5s2p pack I made has a damaged balance connector, so I haven't even balanced it in at least 10 runs. Right now, the highest cell is at about 3.73v, and the lowest is at about 3.57v (at beginning of CV phase). This difference may seem large, but what intrigues me is that the pack balance actually becomes better as the CV phase gets closer to finishing (the highest cell DECREASES in voltage).
The balance of my other pack has also been quite good, but I do still occasionally balance it just because I can.

As for a power supply, I'm running a PC server PS that is rated at 30amps on the +12v line. This power supply actually came bundled with a second power supply in an enclosure that is meant for use in IBM servers (total output of 60amps on +12v line). The cost of the entire enclosure/PSs was only $40, and maybe $10 for shipping. The individual PSs are a little large (not that large, though), but they work VERY well and don't drop their voltage at all with about a 15amp load. Unfortunately these PSs are no longer sold, otherwise I would buy more and sell them for profit :).