I have the original AccuQuilt GO cutter, and quite a few dies. I love mine!!
So, some thoughts here about this particular system...
One, it IS a hand-crank, so if you have wrist/arm/shoulder issues, don't get it. It advertises that you can cut 8 layers... well, you can, but it's very difficult. I usually do a maximum of 6 layers. When cutting with the rotary cutter, I can seldom accurately cut six layers (something always slides/moves/jiggles) .
Two, if you don't have any health issues, but you DO want to use up your scraps, or make your own "jelly rolls" out of your scraps/yardage, then it's well worth the money. I think, (but not certain) that Bonnie Hunter uses AccuQuilt for cutting her scraps for her scrap system.
Three - If you like some of the "vintage" cuts that have curves (SunBonnet Sue, Dresden Plate, Double Wedding Ring, etc), AccuQuilt has them, and doing "vintage" is easier than ever. I really had a blast doing my Dresden Plate - those petals came out SO fast!!
As far as interchangeability goes, some of them CAN use each other's dies - but you need an adapter.
I would NOT get the GO BABY cutter, as it's the smallest one out there and has a limited amount of dies that it will accept, even from its own manufacturer.
Personally, if I could have afforded the Studio cutter, I would have bought it, along with the adapter, as it can utilize all of the AccuQuilt dies.