I own a Lezyne Road Drive in the large size and I really like it, it actually can reach the PSI limit that the company advertises which most other pump manufacturers can't come close to their advertised limits. So based on that I would assume that the MTB Alloy will do the same thing and be able to reach 90 PSI, however I would get the medium size and not the small size to make pumping easier and faster.
Another option is the Topeak Mountain Morph which has very high reviews but a tad uglier than the Lezyne.