I would honestly be surprised if you're seeing rent at $1/sq ft. in the Montrose area, and it's a livable space. Most of the things I'm seeing are in the $1.75 - $2 range. But if you're seeing those numbers, I would wonder whether you could get closer to $1.75/ft with a little upgrading.
Another factor could be that this time of year there is a very high turnover of units across the board. Late spring and early summer tend to be high-volume moving times.
Ultimately, though, I don't think the mid-rise market will crowd out the smaller 2-6 unit complexes. The fancier mid-rises appeal to a certain market demographic (yuppies), and there are plenty of other renters who fall outside that demographic. Many people just don't want to live in a complex with 50, 60, or 100 units.
The demand may also be highly dependent on the sub-market. In the Heights, for example, duplexes, triplexes, and quads are renting almost as fast as they can be put online, at rates closer to $2/ft. A lot of that is the neighborhood "charm," but for as long as I've lived there (7 yrs), the market for small multi-family has been popping.