From what little I know, that Metz is a popular track tyre, but with better longevity than some others.
All tyres are a compromise, except out-and-out race wear or solid ones !
I found PR3 and now PR4 to be excellent in the wet and very durable.
If you are not a hard rider, I would think that mixed tyres would not be a problem. Also that M7RR might not be the right choice.