Fuji,
With regard to the IMCr safety. In the CAA's last 10 year analysis, considering accidents within the UK (which allows for analysis of all of the facts using the matching AAIB reports) there were two fatal accidents involving IMCr pilots in IMC conditions (1 CFIT, 1 loss of control following an engine failure). There was (from memory) 1 CFIT for an IR rated pilot (ATPL descending from enroute into the sea).
With only 3 fatal accidents in the decade it is a very small sample. As I have already said, there is no indication I am aware of as to even the number of pilots with a current IMCr vs IR - let a lone the amount and type of flying they do.
However, as a very anecdotal comments. When I am out at the airport on a cold and rainy day, the aircraft coming in are (in rough frequency) the local charter operator (CPL/IR, locally based turboprops (unlikely to be IMCr pilots), NReg aircraft (almost surely FAA/IR, and G-reg (of whom a number of the pilots I know are IRs and the rest are IMCr holders) - So I lean towards a view that IMCr holders are small fraction of the pilots flying on bad weather days. Of course, if I were based in the midlands, on a grass strip, with no local charter operator, I might have a very different view.