For those that look at the time ratings I put up each day here are some figures for you:

Best Times Top Rated
Races : 12,337
WIN Return : 12,328
WROT : 99.9%
Place Return : 11,725
PROT : 95%

Thats not too bad for any rating system in my opinion considering it has no filters.

Avg Times Top Rated
Races : 12,337
WIN Return : 11,872
WROT : 96.2%
Place Return : 12,058
PROT : 97.7%

Not bad but not as good as the best times.

Best + Avg Top Rated
Races : 6,215
WIN Return : 6,014
WROT : 96.7%
Place Return : 6,001
PROT : 96.5%

Interestingly combining the ratings actually reduces the ROT. Best to stick to using the Best time by the looks of it.

Good Luck.