I think here lies the problem though, it's a more armoured Cromwell with worse vet and costs an arm and a leg in both price, popcap and tech. You have a few useful abilities but they have all seen nerfs or are still bugged (WP).
It's simply not worth the cost and scales terribly which is why pro players like Hans just build two Cromwells. If you stall you can bully a p4 with it but by the time you stall for a comet you will have zero map control and he will have a command panther or panther next to his P4 anyway
How does its vet stack against the cromwell? I wouldn't see issue with mirroring it (the t34s are the same, commit to that sort of design) but for the price difference to the cromwell the comet is acceptable. It has the most armour of any medium now does it not?
As for the p4 and panther matchup, it shouldn't be a no Brainer no matter the enemy lineup, it will Excell against some builds and be less effective against others. Against panthers you would be better off with a churchill and firefly than comets and cromwell anyways, but against p4s you can do no better than the comet. I think that's reasonable.