Hellcats not ambushing are worthless against anything heavier then a P4, in a 3v3 I had 3 Tigers because they killed my tigers and we finally pushed them back far enough to get them back then the one US player threw 9 Hellcats at my tigers and they all died before I lost 50% health on one of the Tigers
When I played as PE the same thing happened with hellcats vs Jagdpanther. The guy I was playing with said "how is that fair?"
According to coh-stats.com M-18 has the x2 dmg and x5 penetration when ambushed and longer gun range.
But the normal
gun penetration of M-18 is twice as low as M-10. Its also slower and less accurate vs infantry.Vet 2 M-10 also gets a 1,5 Penetration bonus instead of M-18 Weapon Range bonus.
My advice - use M-10 or M-18 and 57mm combo.