How much more accurate is a max vet OSA than a tung? Tung has 35% hit chance at max range, what's OSA's?
Full vet OSA AKM costing $80, has 50% accuracy, and a higher rate of fire than the top Tunguska with zero vet costing $75. But bear in mind that I always have some AAA or vetted Igla inf hidden away in front of them, so the lesser range isn't usually an issue for me. I always have a $20 supply truck with my SAM's, so the slightly lower missile load isn't an issue either. I find the extra 10kph speed of the OSK AKM very useful and it often bags me an enemy recon at the start of the game, and also makes me less worried about sending fast forward commands or attack forces (The Igla Inf in fast APC's also help with this.)
Like I said, the tunguska is a great unit, but Pact has many great support units and you can only have 5, so on balance I chose to drop the tunguska to allow me to field other units. I admit it wasn't an easy decision, but when it comes to missiles, accuracy and cost is very important. Vetted AKM's and Iglas are very good value considering their performance.