it just makes things a bit more consistent.
if you turn off all corrections, the car will make a minimally lower power figure but as it is displaying raw load on the hubs the numbers do drop slightly as after a few runs you develop a bit of heat soak in the engine bay. the temp probe picks this up and makes small adjustments to the numbers to keep everything more equal. it makes it easier to see if its what you just changed in the map that changed the power/torque or just the heat soak dropping it. its just a tuning aid.
i've said this a thousand times but numbers are numbers. in my experience hubs and rollers are very close, if anything mainlines read noticeably lower. who cares. its the quality of tune and how it drives that matters.
to be on topic a stock rb25 will take a lot, but it has to be treated with respect. good maintenance, safe tune, no limiter bashing and minimal rpm to achieve your goal. reving it to 8k will kill it quick smart.