The biggest problems with hull down currently can be summed up as follows:
- You still get outranged by tds (not sure about a hulled down Panther)
- It takes too long to move out of the hull down position
- You need Pios to "build" the hulldown
Not entirely true:
- Hulled Down Panther has 62.5 range.
(Also a shit-ton of effective HP with Hull Down and Command Panzer buffs)
- Removing Hull-Down is instant. Vehicle can move straight after disabling Hull-Down.
- All infantry can put tanks into Hull Down.
The biggest problem with Hull Down is simply that CoH2 tank warfare is very mobile by nature and there are very few scenarios in which you'd want to make your tanks immobile. No amount of (reasonable) bonusses is ever going to make that otherwise. It's a similar situation to British emplacements.
Hull Down Panther is one of the best things in the game though, if you can make it work. 62.5 range and 1600 effective HP IIRC if you got the Command Panzer nearby and it can take on two Allied TDs.