Hehe, I never noticed it was called strudel. From what I remember they do sound different. I haven't got them installed anymore, so can't check . I don't like to render the r2r, though. Hitting it at the right input level is too important (which I didn't know before I started using r2r, so maybe I wasn't using the free ones to their full potential)
Honestly, no comparison. That's not because the Strudel programs are bad but rather because the R2R program set is so good.
In addition to hitting the tape program at the right level (I'm with Mplay on this one, I never pre-render stuff like that, I tweak levels and program choice) the differences between the various programs for a particular machine make subtle differences available as well. It's a ton of programs for each machine and a nice variety of different machines.
R2R is the Nebula purchase (aside from the plugin itself) that I have gotten the most use out of by far.