The IMC is very useful and providing you keep current with flying IMC makes you safer. I have a session with a friend or instructor periodically when I fly on instruments from just after take off to DA/MDA on instrument approach.
An acquaintance of mine has done the FAA IR. He is used to doing academic courses including oral exams. He described the FAA IR skills test as the most dfficult exam he has ever done. A two hour oral exam was followed by the practical test where he did various things such as airways flying, various approaches etc. without being told in advance anything about what he was going to do.
The FAA IR is perceived, wrongly it seems, to be easier because there is only one exam, a lower total hours flying requirement and you can count instrument flying done previously towards your hours, up to a limit (not sure what it is!). The JAA IR is more tedious because you have 7 exams (£55 each)usually done in two sessions, plus compulsory 2 weeks (done separately) of consolidation at a ground school. The cost of the academic side is probably about £2,000 and then you have the flying! With the FAA IR you can home study and then do the single exam at any flight training organisation.
The flying you do for the IR you do is the same whether you are PPL only or going for a CPL/ATPL, though some PPLs go for the single engine IR, which is 5 hours less. The only medical requirement for the IR above a PPL is a special hearing test.