Wore a front set of P6000 out in 12,00 miles, but on a Vauxhall Omega, and the rears in 15,000. Not the best tyre in the wet. On the Omega Avon ZZ3 were the best I tried. Check on the load rating, for the MX5 it should be 82 to 83, if the loading of the P6000 is 91 it may make them a bit of a hard ride for the MX5.
P6000s aren’t great. Volvo fit them as standard to V70s (used to, at least - not sure if they still do) and when I initially had my first V70 a few years back it was shod with these. When driving in the wet, I often thought that it might be best if I just took my hands off the wheel and let the car go where it wanted - there’d be just as much chance of it following the wet road as if I actually made any steering input!