Don't count any time in a sim, FNPT1 OR II towards your total time in any class or type of aircraft. The only time it is worth logging in your log book is when its manditory for a rating or type issue. And even then it dosn't go towards total time or MEP time.
But for the purposes of deciding SEP or MEP you will be more up to speed flying the MEP after just sitting your IR. Also and extra 800 for 15hrs in a twin is cheap. Its worth maximum 9 hours in a single at rental rates. Now an extra 15hrs in a twin...
Also as well if you get above 50hrs flying time in a twin (ie proper logged) it means that you can rent twins more easly due to insurance resrictions and also if you go for air taxi jobs you need a min of 50hrs MEP for JAR OPS.
MJ