As a spare parts car, or are you going to have two complete cars?
I like mine so much, I just can't see going back to 1/10 scale. I'm debating whether or not to sell my RC10B4. I have a bunch of very new parts (batteries, MMP with only 4 or 5 packs through it, lots of spares, etc), though, and I imagine I'll lose a ton.
On the other hand, I can see sticking with 1/8 scale for a very long time.