I’ve played in both of the two Rivers 100K tourneys so far. Here are some thoughts:
1) If you look at Rivers’ Day 2 starting stack lists, there are not that many players who make it there with more than 100,000 chips. There will be a handful who are in far better shape (200,000-300,000), but not that many. So while you would be buying in for only 33BB on Day 2, you are not at such a great disadvantage. While the average stack size might be around 120-140,000, my guess is that the median is more like 90-100. Some people make it to Day 2 with very short stacks of 15-30K, even.
2) That said, of course if you can make it to Day 2 with a smaller ($260) buy-in that’ll be preferable. However, you have to get through a lot more players to get there, of course.
3) Rivers also has been doing $30 (iirc) satellite tables in the days leading up to these events. Of course, that is the best value of all, potentially. But again, you have to plow through a lot of people to realize that value.
4) A bigger issue I encountered there is the relatively high number of late arrivals to the Day 1 flights. I was surprised to find that the tournament director sat on-time players at the number of tables he ultimately expected to fill, meaning that we were playing very short-handed at some initial tables. I played a Thursday morning flight for about an hour four-handed, and then another half-hour 5-6 handed. This effectively shortened our starting stacks considerably, especially as they start out with antes right away. So we were playing roughly double the number of hands you'd expect in the first three levels (30 mins each)... Kind of surprised he didn't bunch us all together in 9/10 player tables and then break things up as others arrived, but whatever.
5) If you play a Saturday flight, expect a flood of pros who are there to play BINGO, as they are rolled to buy in repeatedly. This can create either an opportunity or a problem for players without the bankroll to take coin-flip chances at doubling up against one of these guys. (I had one table where three successive pros sat down and busted fast, between 1 minute and 30 minutes.) You will also encounter pros who make Day 2 on an earlier flight, but continue to play additional Day 1s in the hope of building a bigger starting stack than they did when initially qualifying.