I just got off the phone with KanEquip who is our local Great Plains dealer. Funny enough Great Plains is only 40 miles from my house. Anyway, he quoted me a new GP 606NT for $26,700 with all three boxes and a Stealth Pro 6 with the two boxes and it was $22,700. He didn't have a 606NT worked up with just the two boxes, but he thought he remembered them being around $5,000. That would mean you could get a 606NT with the same setup for about the same money. He didn't think it was worth it in his opinion as the stealth downgraded a few parts to "save cost". He thought all they actually did was put the little camo sticker on it.
It might come down to the capacity of your machine as he said the Stealth models were built lighter in a few areas.
Being so close to GP, he has talked with them about places to cut cost on their regular 606NT. He has told them their boxes are oversized. If full he said you can plant around 10 acres per fill. Guys who are buying such a small machine probably wouldn't mind filling the box more often. If you are an actual producer you are buying the 40' model anyway. I thought that was a valid point.