Smart Balls vs. Teneo Uno?

I have a set of Fun Factory Smart Balls, which I adore and use often. The only drawback I've found with them is that -- well, I don't know if I've got a shallow/short vagina or what, but it's almost like the Smart Balls are too big. So I've been thinking about getting a Teneo Uno, because with only one ball instead of two, I figure it'll be more comfortable. If nothing else, at least it'll be another option for me when I don't feel like using the traditional Smart Balls.

I'd love to hear from women who've used both and can give me the lowdown on the differences between the two. I guess what I'm really wondering is whether it's worth my while to purchase a Teneo Duo.

Thanks in advance!