In a similar note am I required to hold a valid MECR for a typerating,
You're holding an Multi-Engine PISTON (MEP) commercial class rating, not a a multi-engine class rating. So your MEP Commercial class rating expiring just means you can't fly multi-piston aircraft for cash.
Does that mean my ME IR reverts to a SE IR?
No. From LASORS:
SPA IR privileges are not type or class specific -
the holder of more than one SPA type or class
rating is required to re-validate the IR on only one
SPA type or class (usually the most complex
one). However, the holder of a ME IR must
revalidate on a ME class or type. An IR SPA ME
will confer SPA SE IR privileges whereas an IR
SPA SE does not confer SPA ME IR privileges.
The key here is "IR privileges are not type or class specific". So a multi won't "downgrade" to a single IR in any circumstance.
If you need to renew you multi IR, it's probably cheaper in an FNPT2. But if you want to renew your commercial MEP, you need to do it in an aircraft (obviously you can do both at the same time if you wish)
P