Hi Colin,
I think there's a bit more difference than just picking out the good ones from a production batch. As a beginner I don't understand the difference on many of the things, nor the value or importance of them, but I went for the "pro" model alto on the basis that I felt my budget could accommodate it and anything that was a bit better might help me in the long run. I probably should have bought a second hand older quality horn but that's a minefield for a complete novice and buying new with a guarantee and a returns policy just felt safer. The pro model has things like rolled tone holes, adjustable high D and F keys, extra struts on some of the hole covers (forgive me I don't know the correct term for them), and of course they claim quieter keying action and greater tone range (I couldn't possibly say). I guess anything they can do to get the feel and sound even a bit closer to a true Yani has to be worth a little extra. Whether or not it was worth £200 more is of course a subjective thing.
I'm not experienced enough to give a qualified opinion but all I can say is that after 3 weeks I'm getting more and more comfortable with it and, unsurprisingly compared to my 85 year old tenor, am finding the keys very fluid and comfortable and easy to get around and the tone more and more pleasing even with the standard mouthpiece that it came with. But then, I've never tried a Yani!
With current issues trying to bring the tenor up to full playing standard I'm getting more and more tempted to try one of their Rosedale tenors on 14 day trial too.