I ran the OGS (
www.onlygoodstuff.com ) Propain kit on my Syclone with some promising results last fall. I ran into false knock issues, and put it away for winter/parts install.
Took it off so i could use it on another vehicle, so no more data.
I think the propane is easier to tune than alky, but is a bit harder to keep an eye on as far as levels go, and can vary with tank pressure and so forth.
I also believe it offers a longer period between refills. It is cheap also. Atomization isn't as much an issue.
I think the alky setups can be done easily and cheaply, and with good safety margins nowadays as well. Mark Larson on here is running a pretty good DIY methanol injection with good results.
Alky-methanol injection crowd is huge with many other cars...the propane users - not that many of them. Not sure if it is due to problems or bad results, but it's worth keeping this in mind if you are afraid of experimenting and breaking parts, and would like a large support audience.
done with my rambling