I currently attend University of Illinois Urbana-Champaign and will be a sophomore. I spent my freshman year at the University of Miami, a school that's similar in caliber, but ended up transferring to UIUC as I was miserable at Miami and live about 100 miles from UIUC. My grades were good, I'll be starting at UIUC with a 3.84 GPA but my goal has been to go to UC Berkeley. I didn't have the chance to apply to UCB after Miami as the deadline had passed and I didn't get in as a freshman. I think with my college grades and EC'S I have a decent chance. However, everyone I've told has advised against it as they say it'll be a a red flag with med school admissions. I have no issues with transferring again and think a UCB education is as good as it gets. Is it worth it?
The thing you first need to ask yourself is why did you transfer from Miami this year? I think that's the thing that people are missing here. Why are you going to a school you are only interested in attending for one year?
The part I bolded says alot in terms of answering whether or not it's worth it. There doesn't sound like a rhyme or reason for transferring again other than "I like Berekley's education that they offer". Thousands and thousands of people get rejected from their dream school for college. The vast majority move past it and make due with what they have. Those who don't leave for reasons such as "they don't have the major I want" or "I was a horrible fit in the school's culture and environment(ie a very religious person going to a huge party school). None of this seems to apply to you. Many come to realize those dream schools they didn't get into weren't really what was best for them. What makes you think Berekley is best for you?
I'll also say see what transferring is like this fall in a new environment before committing to the idea of wanting to do a transfer again a year from now. It is hard. People make a large number of their friends and social groups freshmen year. Things change after that and it gets harder to meet people. Adjusting to a new environment when you aren't a freshmen anymore is tough. There is nothing to ease your transition like there is when you were a freshmen such as freshmen housing or anything like that with people who are in the same boat as you.
On top of that consider what everyone has said.
a) adjusting to a new school is hard. There's a reason so many transfers drop pre-med. Keeping up your grades in new situations isn't easy. And here comes this this is a general rule: the later you are in college the more costly alot of common mistakes people make are. Not adjusting to college and having a poor first semester of college is one thing. Not adjusting well to Berekley and not having a good junior year when you are supposed to be hitting your peak and when ADCOMs are really interested in evaluating the kind of student you are is bad. Very bad.
b) Doing research, participating in meaningful activties and establishing meaningful professor relationships becomes a lot harder when your jumping all over the place every year. It takes people sometimes months to find a good research position or place they can volunteer at or club they like. LEave again a few months after that and you've basically gotten nothing out of those things.
c) Berekley is HARD. It is not very endearing to pre-meds. Medicore advising, intense classes, intense environment; it is very hard to pull off the grades needed for med school there. B grades are difficult to get and entail beating the majority of undergrads there who are some of the most intense and brightest in the country. B's aren't what you want for med school admission. To get an A there really requires dominance in a subject and class over a vast majority of very very hardworking students. Is there anything more than just speculation that makes you think Berekley is what's best for you? Because even if it is the best educational place for you, I would still strongly advise really reconsidering a course of action that involves you going to such a daunting place.
d) Voluntarily establishing CA residency is not a particularly wise decision if you end up doing that. gonnif talks alot about how every year there are CA premeds with 3.65/31's who after two cycles still can't find anyone to bite on them.
Above all else, the question alone shows your mind might not be where it needs to be. Success wherever it comes is what matters. Living these fantasies of going to Berekley because you like it and ditching 2 schools is not what matters. Focus on life and its challenges right now and you'll probably find once you do these grandiose plans more than year away aren't really worth any consideration.