Pub45, flying like Americans is no big problem. If they've flown for a major airline, then they will be up to scratch- there may be small differences in "presentation", but that's about it. Any doubts I have are about their training system- it tends to assume you will follow the ordained path: student, instructor, commuter, regional, then major.
You're probably right, those that succeed in the commuter and regionals pick up the experience they need, and receive further training as required. I suppose it's understandable, their system supports them so well in operation that much of what we learn is superfluous. Climatology is unlikely to be necessary, given the excellent standard of met briefing they can obtain. And if you can have an entire career flying round one enormous country, with everybody a native speaker of your language, does it matter if you don't use exact terminology on the R/T?
On my first day of line training, I spoke to controllers in the UK, the Netherlands, and Germany. The following week it was Germany again, France, Austria. Then Italy, Switzerland and Finland. My R/T had to be standard!
It was interesting, when I worked in the US, to hear the sort of questions the commuters were asking at interview. It was a bit like our ATPL exams- people sweated about them far more than about their FAA writtens. Everything from basic aerodynamics to patterns of lights at airfield were asked. I've never been asked things like that at an interview in the UK- ok, a couple of very technical questions, one or two on CRM, but not a whole bunch of them.
I've also flown with one or two UK captains (CAA licenced, trained in the UK) whose skills seemed deficient to me. In the minority, sure, but they exist. So I guess the short answer is, watch whoever you fly with, learn from if you can, but be prepared.
Sorry about that, the answer seemed to drag on longer than I meant!