Nosewheel1st
When I did the IMC I had it drummed into me by my F/I never to launch off into known IMC conditions - besides the problems already mentioned of calibration of instruments etc. the rating is simply not good enough to enable us to fly in IMC safely.
This sort of b******s comes from many instructors and unless heavily qualified (i.e. suitable aircraft, currency etc needed), that's exactly what it is.
But then your average instructor is in no position to comment. If he ever had an IR, it had probably expired around the time you were born, and since then he's been doing the rounds of the (very) local countryside in as good VMC as he can get. Unless he is doing instructing just to get an airline job, in which case he's probably had even less time in actual IMC
Of course, the instructor isn't going to say
"I don't recommend you fly any of our planes in actual IMC because
a) they don't have adequate instruments
b) half the instruments that are there don't work
c) those that do appear to work haven't been calibrated EVER
d) We never paid to get the thing FM immune so you can't fly IFR in controlled airspace (even if you had the legally required instruments, which you don't have because we won't pay for maintaining them)
e) I wouldn't fly that piece of junk in IMC so I don't see why you should, and if you wreck it I will get dragged before the CAA for letting you do it...
"
There is little difference between an IR and an IMCR (in the GA low level flying context) if both are equally current, and there is little difference between an IR and the IMCR if both expired 5 years ago.
The IMC Rating is a great privilege to have and should not be constantly knocked as it is, by certain individuals in the trade. There are certainly problems with it but they are little to do with the rating itself; they are mostly concerned with the appalling standard of aircraft available for general hire, and with the fact that most people that are attracted to GA in the UK cannot afford to keep sufficiently current to make good use of it.