If you care about the quality of your education, then you are unlikely to come out with better or more widely accepted qualifications/results by going through an American system. Only if you compare poor schools/universities in UK/Europe with the best US ones is there no real contest. To attend the best ones in the US is likely to involve high expense in addition to not being in the area of former friends. You are correct that switching systems involves a lot of work, both on paper and in terms of patience and effort - I am not qualified to advise on this but I know of one or two who have done this and lost years in the process. On a general note, be warned that you are likely to see past places/friendships/experiences in a significantly rosy way after years away and it is not unlikely that you would find things do not meet your expectations on return.