For me the thing that makes this system a non-starter is its retention of single seat constituencies - the only argument for which is that voters get a single identifiable individual who was on the ballot they voted on - while at the same time depending on being able to parachute in a representative who may not have been on the ballot, or who was, but was rejected by more voters than the FPTP winner. This makes a mockery of any claim to local representation for the electorate.
There are better existing systems, STV being my choice.

I can see that there is an advantage in maintaining the single-member constituencies (with or without the MwoCs) but I'm not convinced that this is a simpler system to understand than the other PR systems floating around. Still, we don't need to understand the intricacies to know how to vote and we would probably get our heads around the terminology if we are sufficiently interested in those things.