Maybe doing some other speculative maths would show that it would at the very least take longer than 400 hours to max out a character? I don't know.
Maybe we can use my NV save files as a sort of bench mark to see what level we'd be using the NV system. (I'm not good at math so someone else will have to do the calculations.)
I reached the max level in NV somewhere between 163-179 hours of gameplay. (so somewhere between those two save files.) And my last save was at 423 hours. (everything completed.) So if you can reach level 50 in that time frame, what level would I have reached by the end if NV had no level cap? (this of course is all very rough and will still be speculative but it's at least something to gauge?)
I've been making up in my head that even if you doubled how fast you leveled in NV you still wouldn't have been able to max out a character using F4's perk system in 400 hours of gameplay. (but like I said, I dont' know maths.)