High Fuel Consumption: Yup, eats it.
High Oil Consumption: 1L for 1k miles is what mine is roughly using. I am pretty sure a few piston engines out there, the manufacturers are saying that is a normal level of oil usage, and they aren't designed to inject it.
Apex seals: Ah the great internet meme, sure they need to be rebuilt more than a piston engine, but are cheaper to rebuild and often is an unfair metric. Mines done 40k since the previous owner had it rebuilt and thats because a Mazda coolant seal failed.
Quickness: I mean that is subjective, it is more than fast enough with a beautiful chassis. It's been what nearly 12 years since the RX8 went out of production. We didn't have the Golf R's and A45's back in the day, they were all FWD mid 200bhp hatches. With a few JDM exceptions Evo/Subaru. We are definitely spoiled by newer tech.
RX7 is way more rattly than the RX8. I am currently trying to get all that sorted. There are quite a few differences, but I never feel short changed jumping from 7 to the 8.