I have added a thrid article on the subject of converting music.xml/midi files for use with Sonic Pi, which gives some practical points to look out for when using the conversion script. It will not make much sense unless you have read the first two article beforehand
You can find it here
The first article is here
The second article is here
rbnrpi 
Pingback: Sonic Pi plays Mozart’s Requiem in D Minor | rbnrpi
Thank you for your comment Mike. I would be very interested to see your Ruby sfx class. That was one of the things I was thinking of. In fact it would be good to get sfx support added to Sonic Pi. I also have a (rather old) version of Cakewalk, but I have not used it for some time (its on an old XP machine). I get a buzz out of seeing how far Sonic Pi can be pushed. The results are not as polished as something like cakewalk or logic pro can produce, but they are still pleasing, and you feel that you have had more to do with producing them.
Robin