Depends on the level of modifications..
I believe the S8 has the oil problems sorted with the TT setup by then.
If you're looking at limited modifications, they're both going to be very reliable.
I've had a big hp 13BT before and they're definately a good thing, just need to look after it very closely. Im still a nissan man tho, which is why I still drive a GTR
If you are serious about your track performance, I'd go the RX7