Phil,
If you are only going to get one gun, I'd consider the Sata RP3000 instead of the minijet. Don't get me wrong, the minijet is a phenominal gun, I've got a few of them, but it has a very small color cup, You can get a 1.2 tip for the minijet which is what I'd use, that is the absolute smallest I would use for primer, and it will give you decent flow for clear. The 1.4 would be even better, but it's a really small gun for a tip that big.
My personal opinion is that the RP3000 with a 1.3 tip would be the most versatile gun for spraying primer, base, and clear.
I've sprayed probably 1000 + gallons with my RP3000's in the last 2 years and the gun still amazes me. As far as I'm concerned it's the best gun on the market.
Just my opinion though
Jeremy