I had a choice whether to buy a 17" Brodie Bandit or shop around for a bike a hair smaller. I liked the feel of the bike in the store so I bought it.
I allways regreted it after.
I think a bike you can get used to it. BUT. If it dont fit like a glove then it never will fit like a glove. There will always be something sloppy about it.
I am sized for a 16" Kona or Brodie for the technical stuff I 'try' to do.
I was quite happy on my 17" bike untill I got into the rocks (which is where I like to ride).
I would borrow as many types and sizes as possible and ride them where you do your majority of bikeing and find one that fits perfect. It might take some moving around of suspension adjustments and seat post adjustments(ask for the owners OK first)
I have an old 18" Fuego that I rode for years. The size was small but still it was called a 18" because of the design. I rode nite and day summer and all winter for 3 years till the bike was beat. That bike fit like a glove and I could make that thing handle a lot better then my brodie just because it fit me and I became part of it.
I will be looking to get another high end bike next year and I will take my time and find a perfect one.
Up here in Canada, KONA has a demo at various parts of the province at different times so you can try different bikes out for free. All you need is acredit card and away you go
Choose wisely junkyard