"Allstar without the attached OS" is just Asterisk with app_rpt. Asterisk runs on many OSes - Linux, BSD, Windows, etc... Just need to compile it with app_rpt.
Allstar takes it a step further, building a network on top of Asterisk and app_rpt. They provide a distribution of Debian with Asterisk and app_rpt pre compiled, with all the heavy lifting and configuration already done. You could do it all yourself, but why when you can save time with the distro?
The issue I see is not with the Allstar distribution, but rather getting DRAWS to show up as a compatible device for app_rpt. The URIx and other similar radio interface were specifically designed for Allstar, IRLP and the like.
A driver may be needed for use with Allstar. If this is something that a lot of people are interested in, I could take a stab at it. Just need to dedicate the time and a board. Though, I feel that the exercise may be a little in vain, using DRAWS for just going from a radio to Allstar is seriously limiting the power and capabilities of the board. A URIx would be easier, since it's the right tools for the job kind of thing. Plus, it's cheaper than a DRAWS board.