That was too much it was in a fair play as it was. I mean 470mp - 135fuel for a unit that can be take down very easily. It should deal the same damage as the Panther or Vet Faster in fact all Assault guns should vet faster.
It has 5 lvls of vet and it cant handle infantry! I have taken down 4 t34s and 2 HT with it in one game it still was only Vet2.
JP4 out DPS the Panther, it deals the same damage(160) and have a much faster Reload(4.3-5.2 vs 6.1-6.4) and 10 more range, it is weaker in penetration(200/185/170 vs 260/240/220).
JP4 have the smallest size(17) of all TDs and Medium Tanks(the rest are 22-24), it is even smaller than T-70/Luch(18) and Stuart(19), this makes it hard to hit at medium/long range with inaccurate weapons like tank guns and infantry AT. However I do agree the MP bump is unecssary.