For those having issues with the HQ art pack locking up the emu, I have experienced some of that too. I have been meaning to finish up with what I have (carts, backs, titles and snaps) and release them. They will all be scaled to to below 512x512 as nes suggested. At first I was wanting as big of resolutions as I could get (often leaving these new pics at full size) but after seeing that just having a better source pack to downscale from is making all the difference. I do have to admit that you really don't see any real quality difference with the higher res pics though, so scaling down will help. I'm in the process of moving right now, so I have no internet for a few days, and will be pretty busy.
I'm really looking forward to trying out the new rumbles!