I just did Boundary about two weeks ago. From the Queen Mine to Boundary and back it took us 12 hours, but we're slow. Steady, but slow.
There was also a lot of snow on the route, and we spent too much time mucking around in the scree fields. If we'd gone straight to the ridge after the first slope, we probably would have shaved 1.5hrs off our time.
There was too much snow for us to try for Montgomery.
If I was going to do it again, I'd hike in to the Trail Canyon Saddle and camp there instead of at the mine. Would make summit day much shorter, and hiking out afterwards wouldn't be a big deal.