haven't read the whole thread, but i'm gonna bet that compared to some of you, i'm a wimp...
for "regular everyday shooting" my personal limit is along the lines of "if the felt recoil is worse than 30-06 through a 1903, or 1917, you can count me out". now i have fired larger, more powerful rounds, up to and including .50BMG. but I've never OWNED anything that shot ammo stronger than 308/30-06 class.
heck i don't really ever foresee me even buying a carbine or "brush gun" type rifle in a "full power" (ie aforesaid .308/30-06 class or larger) rifle cartidge ever again. full power .308 in a lightweight short barreled bolt action (the Remington 600 my father gave me) just wasn't a huge thrill.
Figuring into my outlook on this is the fact that ALL of my shooting is done at a range, I don't hunt, so i don't need a short, light "brush gun" or something capable of slaying an elk from across the valley, and even if i were to start messing around with something like 3-gun matches, and on a lark wanted to use a MBR type like a M1A for it. i'd be doing it for the fun of it and wouldn't care if i finished last, cause i'm too fat, slow, and cripple, for the size or weight of my rifle to make a noticable difference
ETA: there IS one gun/round combo that some might find a bit much, that i plan to have someday. i want a 45-70 or if i get adventurous 45-110 sharps repro. but we're not talking about super stout loads here, i personally find BP or BP substitute loads in 45-70 etc to be milder and easier for me to handle than some more modern rounds.