Lee Martin was booked in for an SC race but withdrew as the Tamiya wasn't ready in time - I would guess this means there's a Tamiya SC coming of some sort.
The 511 wasn't better on the track than the 501X - the main difference was the cell movement - which only really mattered for nimh cells (yes, it's that old) and most / all drivers use their lipos at the same position as the 501X - further back so they fit under the centre.
All the rest was the same - though achieved in a different way and with cheaper materials and less in the kit for more money. Bargain!
That's just me opinion though as I'm a 501X fan - the only reason that car wasn't as popular is simply because it was the first and they had no team drivers in the UK.
I don't think Tamiya listen to their team drivers - let me know if you know different. I imagine they might come out with another car thats possibly not as good.
Again.