The panther actually matches up poorly with the IS2 even if you factor in the difference in Mp/Fuel. An IS2 for only ~5 more popcap is anti everything squad wiping, but still beats the panther. Neither can really kill each other due to the high hp, but the Is2 will continue to have a large impact vs infantry regardless of the panther, unless it in fact blasting the panther.
The panther on the other hand is basically an MG platform vs infantry. It could probably have slightly stronger mg's now that the cost is all the way up at 185 Fuel (I remember when it was like 145, though it does have OKW mgs now?). It seems relatively good when compared to mediums or other TD's but the panther is in a peculiar spot vs heavies b/c its your "best" counter but its not actually a great counter.
I don't disagree at all and I don't think my previous post did either.