Another n=1 experience:
Graduated from a top UC
All my pre-reqs were completed post-bacc at a smaller newer CSU much later
My personal experience was:
1. Even the "big" classes as my CSU were smaller than those at my UC (75 vs 250 for basic Chem)..fewer gunners and so, if you're motivated, you can get more attention, help, and build a closer relationship with the professors.
2. I found it easier to get better grades at the CSU; I've debated this with myself a great deal - was it more focus (older/wiser), was it smaller classes, was it easier grading, was it less competition with top scorers - probably a little of each.
3. My CSU had plenty of research going on in Bio and Chem - fun stuff...again, fewer gunners so while it's not an endless supply, you might have a better chance of getting to know the PI and getting more opportunities
4. My CSU vs. UC had a different personality of student; many students at my UC were "settling" and had been on wait-lists to Ivies, had long term plans and followed them whereas many students at my CSU were somewhat new to the game and seemed to fall more into the "less informed pre-meds" category... which has pros and cons.
For my own kids, I'm honestly torn - I am "loyal" to my UC, loved my experience there and the sense of pride (goeth before the fall) I get from it, but I think the CSU gave me a really solid education and opportunities to flourish that weren't at the big UC. I was more anonymous at the UC - it took more effort to get to know professors.
TLDR: Ivies are only ones with name value recognition/connections; Education is what you make of it and CSU should offer comparable opportunities with less competition and $$