The way I see it, if you are going to spend money on new stuff, you may as well get the best thing going. To me that is an A123 pack. Sure, we can reminisce about what was, and why this is that and so on and so forth. I have Eneloop packs as well, but I am still replacing them with A123's as time and money warrant. Where I have really seen NiMh perform badly, is on ignitions. The Eneloops are OK for this, but I have been using a lot of small Lipos I have had floating around the shop for this purpose.
Abu, if you are new to gassers, then this is another battery area that you need to think about. It sucks to have problems here as well. As many times, if the power drops off of your Ignition battery, the Ignition goes into a 4 cycle mode, firing every other stroke. I guess to preserve what is left. This can be mis diagnosed as a mixture issue. It is very important to watch your ignition voltage, and keep it fresh. Of course, an A123 would be good here as well. But a NiCd would be better than a NiMh in my opinion, because of the internal resistance.