Melta isn't really too powerful(maybe a wee nerf to damage, to make room for the multimelta to actually have a purpose) the problem is all the other antitank options are awful. Powerfists, rokkits, lascannons etc. need a buff against armour.
Actually at around 100m most shots will hit dead center of where you aim. I forget what the rain map was called but I could loft rokkit shots into the back of a rhino at B from A hitting the exact same point everytime. The initial travel arc is randomized but there is a certain sweet spot for range where all shots hit the exact same location. Think of it as a randomized S curve where all points intersect at a certain location. If you get it just right you can usually hit people on walls behind cover at extreme range, but finding that sweet spot is friggen hard.
imo they need a slight damage reduction on vehicles, but go back to having no damage drop off (or very little). Way I'm thinking is that'd give the Multi-melta a bit of purpose again. Right now it does next to no damage unless you're at the same range that the regular meltagun does the exact same...so why not take the melta and be faster? If there was no damage drop off you could choose between being a bit more mobile and carrying a melta bomb on a Tac or being able to fire longer and from further away with the multi-melta. Also recommend the slight damage reduction to compensate for the no drop off, that way we're not one-burning vehicles from 30m away. Might also make it usable against infantry again (Somewhat), seeing as to kill them now you have to be up their backsides and burn them with a full heat bar to down them. With how long the melta's cooldown is being able to burn 1 infantry unit down and then having to wait for a long time seems more fair than it was before with being able to nuke them down then have the weapon cooled down within a second or two. Edit: And Rokkits USED to do good damage to vehicles...not sure why that got nerfed as drastically as it did.
Also remember thanks to trukk and wagon atrocious controls if it clips anything you might as well abandon ship because that melta is killing you long before you regain control of your vehicle.
Rhinos are the same way. I've had them go belly up trying to flee from a Fire Dragon because I clipped a small rock that sticks out into the road. I really don't like that the Fire Dragon can gain ground on tanks so fast and still out maneuver their Tactical marine counterpart in melee
At least you can rotate yours and drive straight to get out of a jam. We literally have the 100 point turn of doom from austin powers in certain spots.
This is all subjective so disregard if you wish. I play both orks and chaos fairly regularly and I find the rhino WAYY easier to drive than the trukk. The trukk simply bounces around and slides FAR more than the rhino in my experience.