If you are IFR proficient in a single then it doesn't need to take a lot of time to transition to the twin especially if the avionics are similar.
There are obviously many different multui engine aircraft out there but if you look at the most common training twins; the instrument approach speeds are either the same or within 5 knots.
Which means you processor speed (brain power) can remain the same.
Here is an option that you may not have thought of yet:
PPL SEL
ME add on
IFR , about 30 hrs in a single and finish up with 10 hrs in a twin.
The IFR is a rating and therefore carries down and not up.
Which means if you do the check ride in a twin you get both IR ME and SE.
The dual training for the IR counts as PIC since you already hold a ME rating.
CPl SE
ME add-on to the CPL, which is once again all PIC since you are already rated.
The above option gives you more ME PIC time and is only a little more expensive then the SE route but not as expensive as all ME.
Last edited by B2N2; 19th March 2012 at 17:29.
Reason: I'm getting more dyslexic by the day