My assumption is, that better players are less likely to call in late position with 6 8 o (for example), so they would not be in a position to crush you when the flop comes down 5 7 9. Is there any truth to this?
Bad assumption I think. BUT HUGE BUT! I to do not have any experience with big buy-in ring games.
I think most poker schooling, either from books, or articles or forums will concentrate the efforts on understanding the game and at least make an attempt to tighten up true noobs. It is the guy who expects to get lucky that is the target for the 'education'.
That said, watching Poker tourneys, and HSP will show that it seldom makes much of a matter what starting cards one holds, and more matters on how they are played.
So it sort of boils down to being rolled for the bigger games, and being able to withstand the crushing defeats at the fins of the fish......
I too have that nagging suspicion my game is more suited to much bigger buy-ins than I am willing to afford, but alas, barring a miracle, I may never find out...