vicididial doesn't use libpri. asterisk does. you'll need to find out what libpri provides and see whether it is required for functions in asterisk that Vicidial uses. start by finding out what features/functions/modules in asterisk rely on libpri. Likely Dahdi.
Next you have confbridge vs meetme. Since all of Vicidial runs on meetme, you would need to rewrite every call to any meetme function (be it a change or merely an information request) to call the equivalent confbridge function instead. And don't forget to load test the confbridge functions to see if they are reliable when the dialer is making these requests at the nanosecond level (Vicidial's perl scripts use hi-res perl timing to keep the system pumping along at a good speed to avoid switching delays that are otherwise unacceptable without the hi-res timing).
that being said, if you skip the "logged in agent" functionality, there are no meetme rooms. remote agent functions can be used ... but nothing that allows real-time agent-viewing-client-data will work without the meetme room. NOY because they are connected directly, but because both are invoked at the same moment in different aspects of Vicidial (web vs dialer). The Agent Web Page (on the Web server, to view the client data) when logged in is activated at the same moment the meetme room is invoked on the Dialer. These functions do not interact directly, and they can happen on different hardware, but they do interact by passing data across the mysql db (rapidly) when they need to ask or tell the other something. Thus you could have a meetme room in a Linux dialer hardware while the agent screen resides in an OS X web server. If you get that stable ... start looking at Meetme vs confbridge.