Edinburgh, as far as my dealings with them have ever went, have a bizarre admissions policy, which probably keeps this notion of eliteness they try to project going. What they say is, meeting the entry requirements (BBBB for them) will allow you to proceed to the selection phase, where everything will be looked at, and your app will be considered on its merits, not just grades. As a result, its perfectly plausible that AABB students that were rejected from Glasgow get into Edinburgh, but its also possible that AAAAA students are rejected from Edinburgh. They have a policy of favouring the locals, which makes people on TSR down south think they're super elite ('my AAB friend was rejected from Edinburgh but accepted at Glasgow, they must be second rate'), but much of this has to do with the inordinate amount of English applicants Edinburgh and St Andrews get. I'm sure I saw a statistic a couple of years back where it said that more Scottish students in the top 10% of their classes went to Glasgow than anywhere else in Scotland- which is explained perhaps by the fact Edinburgh do draw from lots of private schools where AABBB probably isn't anything special- just because you have an anecdote of a couple of high attaining students who were rejected means very little.
Back to point- I agree with Foxo, if you were wanting to go to an English law school, you should- because its going to consume your time and money if you go the long way round. Like Scottish medical schools, I wouldn't say any of the big five in Scotland for Law are any better or worse than each other, as arbitrary non-academic factors such as where the partners of your prospective firm went to can be more important. Entry requirements are no measure of quality either- Edinburgh keep theirs low to keep application numbers high, St Andrews get lots (for general courses) for the few places they have, and can get picky. Glasgow in this sense is probably closer to the truth- if you exceed what they print in the prospectus, theres a high chance you'll be made an offer of sorts.
And didn't Lib go to Aberdeen as well?