I think the dx3s has some added features. Like the semitry or something like that. The ability to read the temp of an engine or motor if you have the extra components installed. Maybe more to it then that. The DX3R has more bells and whistles then I've been able to use.
IMO RPM is the better way to go. Alum parts have there place in certain areas. Bulkheads, differential cases, stuff that is more solid and doesn't take a beating from impacts. Integy has a bad reputation due to arms, wheelie bars, shock towers, etc getting bent really easy. They do have a few items that have held up really well for me. I have a bulkhead for the rustler and an alum transmission case for the pede/rustler. These parts don't get abused like the arms and towers do. The plastic can break but it also has some give to bend a bit, and will come back close to the original shape. Alum once it's bent it stays bent, you bend it back it weakens it. Some of the off brand aluminum parts also have a fit problem. For example some cheaper offbrand carriers that are made from alum may have more slop in them then you would get if you bought the original alum traxxas carriers. The bearing may not fit as snug. I haven't had any problem with the Fast Lane Machane Alum parts. They have always taken care of anything I broke also. Integy doesn't have a warrenty once you touch the part or install it. Fast Lane has a great warrenty the same with RPM. Although the RPM part that I have broken I didn't bother with the warrenty. Just bought a replacement part.
Check ebay for your revo parts. You can get 4 of the 3.3 axles for a fraction of the price new, same with carriers, and .... Well all the traxxas/revo parts can be gotten fairly cheap for the ebay chop shops.
