Crazy Gal
If you go to an approved JAA training provider in the USA you don't have to redo the CPL skills test. As birdlady says the UK CAA has given approval for the training to be done at specific locations in the US, which, on completion of training, will be able to issue a JAA CPL. The IR is different though, with the test having to be done in a JAA state, although some of the training can be done in the USA. I believe European Flight Training in Florida do that, with the initial training done in the USA, but the final few hours and test done in the UK.
To get an idea of costs you really need to find out how much its going to cost at a few FTO's both here and in the states and just work out an overall cost for each. I've done that and am going to Naples Air Center for my CPL, but I'm going to do the IR in the UK. The 28 hour multi engine CPL at Naples done in entirely in a multi engine aircraft is going to cost me a little less than the standard ME CPL in the UK (20 hours single, 8 hours multi), and that includes all my visa fees, flights, accomodation etc.
The main reasons for me going down this route are that I will get more multi hours for lower cost and flying in Florida means hopefully the weather in January will be better and will allow me to complete quicker.
If you've never flown in this country before I would be cautious about going abroad to do your advanced training because there are differences in RT and a few other issues, and the last thing you want to be doing when you're completing your IR training is coming to terms with these differences as well.
As regards whether you'll be looked less favourably upon because you've trained overseas? Well, my personal opinion is that is wont make much difference. If an airline specifies they want integrated graduates only, well you're not going to get a look in whether you went modular in the UK or US, and if they don't specify integrated, they probably don't care where you trained, just that you are qualified. Having said that, I haven't first hand evidence that this is true, and its just my opinion.
The one caveat to this though is that I have heard that french airlines have in the past specified that they want applicants to have trained in a JAA state, not at an approved school in a non-JAA state.
Hope this helps
PW