i 'mostly' agree with gijoe. i've had my tc3 for a couple years now, and am ready to make the jump to a new platform just for the sake of trying something new. i don't think 400 on it's own is that much of a limiting factor (i mean, how many tmaxxs are out there!?), but when you start to add in the hundreds and hundreds of dollars in spares for things like diffs and bodies, then figure you need to replace that in 10-12 months, it definately becomes an issue for many people.
i had a chance to look at a 415(?) last weekend up close for the first time, and it was VERY nice. if i knew there was a reasonable (ie 2+ year) product life for that model, i'd seriuosly consider buying one.