The only difference that the reviews mention is the metal construction. Has anyone tried both? Is there any significant difference? Are the extra $50 dollars in the Pro price worth it?
Lensbaby claims the focusing ring on Pro is smoother. I have the non-pro, and yes, it is a bit sloppy, but never bothered me.
I was just looking at this the other day. I haven't actually touched the Pro, and so haven't physically compared the two, so a better answer will be from someone who does. But I have used the non-Pro version, and I did find the plastic ball-and-socket configuration less than smooth — which is what they're promoting with the new metal ball-and-socket. So, yeah, the metal construction is the main difference, but I don't think it's insignificant. It's not just a matter of durability, since it's a functional element that's constructed differently.
Digital Photography Review recently published a review of the Lensbaby Composer Pro and Sweet 35 optic, and in their conclusion, they note:
If you're interested in the Lensbaby system, the rest of the review is well worth reading.
↑ that's the "off-topic now" line :)
I think the name "Composer" is apt, by the way. It's appropriate for Lensbaby shots where you're working slowing and carefully. The Muse, on the other hand, is much more fluid and fun. It's also considerably cheaper.
↑ and that's the "way off-topic" line
My favorite, though, is the Lensbaby 2.0. The new optic swap system is cool, especially if you're interested in pinhole or zone plate, or if you get really into it and want to change between plastic and glass and so on. But the older models are considerably smaller, and the flexible tubing more flexible (and less squeaky, something I find a little bit disturbing with the Muse).