The usual........too many choices. I have trouble just picking out a good salad dressing off the supermarket shelf. At least you only lose $2 if you don't like it. Get the wrong R&R cart, if you can't figure out your needs, and you lose $100 plus.
I remember when I bought my R&R cart in it's infancy days. The only one available was the original R10. Been happy with it ever since.