The problem with real world one vacuum pump IMC is that when the pump fails the gyro starts to wind down which then causes it to gently roll over with you of course initially following it.
This means that you first indication something is wrong is when the there is disagreement between the instruments which will initially cause confusion and by then you are almost certainly in a unusual attitude which means you first action will have to be an unusual attitude recovery
I had this scenario happen in IMC on a bumpy day in a C 172. The fact that this airplane was so forgiving made the outcome OK but the initial transition was very ugly and I am convinced if I had been in a High performance SEP I probably would not have survived.
The take away for me was that all the partial panel training I did in no way prepared me for the shock and mental confusion of instruments not agreeing.
From that day on I have never flown an aircraft that did not have dual vacuum pumps in actual IMC. The best set up IMO is a dual vacuum pump set up plus a standby electric AI