For 2+ crt stone production model should be good enough. The difference between production and professional models is 6x and 10x magnification correspondingly.
I agree, even at 6X the production model has more advanced optics than any H&A's viewer I have seen.
On a 0.01ct 1.3mm diamond the 10X has an advantage.
As soon as you get it annoy all your freinds and co workers, and retailers - look at their diamonds so you get to know what you are looking at