Hello Andy,
I suppose I'm somewhat of a long standing MG user (since the original MG 1 Beta release), but I haven't tried tracking with it in Sonar. I was waiting for the features in this MG2 as I wanted it to have better response/less erroneous/omitted notes when playing faster.
However, I would definitely choose (b) as I do want to record it within Sonar. Scook, I believe has done quite a bit of recording with the older releases and possibly might chime in with more details.
Regarding using MG2 in standalone and to route it Sonar, this guy on KVR suggested the following (I still haven't tried though):
The way to route MIDI around the place without using physical ports and leads on 64 bit OS has just been sorted by this piece of software-> loopmidi.
Each port you create has a name you have given it, and has an in and out.So load your generator in a host, and use the MIDI out of MIDIGuitar2. I'm hoping JamOrigin would have the official release of this VST soon so we don't have to go through all these hoops....just to be able to record.