Su-39 is a premium ground attack aircraft. Why does it HAVE to be good in ARB. Does it make tanks go boom in GRB? I Assume so, you arent calling for better AGMs. As you pointed out, Tornado Gr1 sucks in ARB at the moment, it has a higher rating than most Mig-23s and is so handicapped (tiny CM count, wrong missiles, missing features, etc) , its actually painful. But that doesnt matter, its job is to drop bombs on bases, not dogfight Migs.
So giving the Su-39 significantly better missiles isnt going to change anything. The only reason I reckon its 11.3 is because its premium and soviet. If it was anything else, it would be 11.7. Again, RB rating is decided by a jets performance in BOTH GRB and ARB. This is why some jets have wierdly high BRs. Looks at Gr7 and giving it better missiles, would just result in a higher BR.
but I guarantee its BR is 100% based upon its GRB performance not ARB perforrmance
At the end of the day, it IS a ground attack aircraft, that was what it was designed to do. It might have had some enhanced A2A capabilities, but it was never designed for an air superiority role, only improved defensive capability.
But what exactly do you want, the ability to take the Su-39 into an ARB match and walk away with multiple kills every single match with little effort? To be able to 1v1 a Tornado F3 or F-16?
If you want to dogfight an F-16 or F-14 or something else top tier. then you should be in the Mig-23 or Mig-29 an actual air superiority fighter. If the Su-39 EVER got the point where it “could” actually take on top tier jets in air to air combat with the kind of ease you seem to be advocating for, then it means it has extremely powerful missiles. Such as what the A-10 and Su-25 are like with all aspect missiles at a BR where most jets dont even have CMs. and I think we can all agree, that sucks.
So no, I dont think giving the Su-39 such powerful missiles that it would allow, what is a slow, subsonic ground attack aircraft, the ability to go toe to toe with top jets. That would just break the game, especially considering its a premium.
So prehaps instead, advocate for seperate BRs for aircraft in GRB and ARB. That way for GRB it can be at 11.3-11.7, what is likely right for its CAS ability, and then 10.7-11 for ARB, I’d guess about right for its A2A ability.
The Harrier Gr7 has an RB rating 11.7 and its closest equivalent is the Sea Harrier FRS1, which has an RB rating of 10.7 which I think this is about right. So its a full BR higher, purely because of CAS power.
So with this division in BR, you’d see many aircraft, not just top tier jets, drop maybe as much as a full BR in ARB, whilst remaining at a fair and reasonable BR in GRB. It is the ONLY solution that would actually work. Because you cannot balance jets by giving them capabilities so far beyond anything else in any match that they dominate, which considering the Su-39 is a 2008 jet, is exactly what would happen if you gave it 2008 missiles. It quite literally would have missiles 20-30 years ahead of anything else in the game.