I have been very tempted to get the SU-39 and i was wanting to get some feed back from people who have it. I should clarify that im not going to be using it to grind out the russian air tree i just want it due to its CAS capabilities
I have used the su-25t a good bit which is basically the tech tree copy.
It will not be good in uptiers fighting top tier spaa. However, as long as you are not dealing with those, it can work pretty well. I have not used the ARM on it yet but from my testing, they are not very fast and are easy to shoot down.
I would suggest you get the tech tree one to save the money but if you are dead set on getting the premium one over the tech tree, wait for a 50% off sale.
Su-39 has solid close air support capabilities. In the recent updates it’s “anti anti-air” capabilities were improved, and it’s probably going to have its battle rating increased because of that. It’s a good airplane—a good Su-25 with smart weapons at bit higher battle rating.
Worth it? Sincerly no, if you aren’t in full blown close air support and can afford a plane mostly to play alongisde other vehicles, you might as well get the tech tree counterpart (Su-25T), which have some differences but those doesn’t make the Su-39 exceptionally superior, but still is.
As @markimash said—wait for sales, in my opinion no vehicle in War Thunder worth the full price, never was and never will, as also wait for battle rating changes to be sure if it will fit yourself a good line-up before getting the vehicle, since it’s planned to have its battle rating changed, though I’ve haven’t seen someone contest that it shouldn’t be changed.
Used to be pay to win over already great su25t but now its moving up to 11.7. It has 2 kh31p instead of 2 weaker kh58u and 2 broad band kh25mpu over nothing. And kopyo for r73 slaving.
I guess you can buy it during discounts period. But before that you should watch vids and read people opinions AFTER br changes. Especially about uptiers. If they happen too often you might just go for su30mk2/mkk instead (mkk for more and better antirad missiles).