Jonathan Miller did a Double Traverse and had some comments on the route:
So I made an attempt on the double traverse today [12/25/2015]. ( www.strava.com/activities/456195994 ) I realize now that the official BRT is in fact one route with no alternate routes. But I didn't strictly follow the BRT in both directions. I do like the the alternate route back via the Quarry Trail since it adds some extra challenge with steep scrambles and rougher trail. I also chose an alternate route from Mt Mack to Round Pond to allow for more running near Round Pond. And finally an alternate route down from Mt Major at the end via the Boulder Loop Trail since the blue trail is so over-used. So not sure if others would prefer a strict out and back of the BRT or a route something like this. I'd like to get opinions from other runners. I think the alternate routes are more aesthetic and put less of a burden on the trails. I'm still looking to see if anyone else has done this traverse, parking lot to parking lot, by this route or any other.
From his Strava:
What amazing weather for this late in the year! I did the second half in shorts and a t-shirt! I'm still trying to workout an aesthetic route for this traverse. I know I could do a strict out and back on the BRT, but the Quarry Trail really needs to be included due to its steep scrambling. It definitely needs to go parking lot to parking lot. Maybe staying on the BRT to included Mt Klem both ways would be good, but I like the orange/red trail that spends more time around Round Pond instead. I also chose the Boulder Loop Trail down from Mt Major since the blue trail is so steep and over-used. So this is just about the best route I can come up with. I got off track twice around Gunstock summit, so that added about 15 minutes. My total time was 6:07:24. It totally kicked my butt today. I haven't been doing big miles or elevation lately. I'm sure others could do this much faster. I'd really like to know if anyone else has done this or a similar route.