You're absolutely correct. It's always best to consider all the characteristics of the app design. So, I'd like to hear your alternatives to a Back button in your experience. Even the example linked below, Sidetap http://http://sidetap.it/, it toggles between the menu button and the Back button. An anti-pattern that I wouldn't really recommend.

The frequency of use is a variable between apps and users. Hopefully it's been taken into consider during UX / design.

This is what initiated our discussion. We simply didn't like the bottom menu bar that had 3 to 4 options and an elipses. The elipses takes you to another screen that lists the remaining options. It was a developing crutch for too many nav options. Our nav has 7 items this release and 8 to 9 next release. It is text only and the reason is because we limited each item to a 42px+ tap zones. We had issues with iconography as well as keeping it simple.

The opportunity for expansion is a positive feature of slide menus, no argument. In fact, that was the strongest argument for it initially and probably the single most reason if we convert to a slide at a later time. However, the counter argument is that if our navigation gets so wide as to scroll off screen then maybe we can reconsider the structure and revise. Opportunities abound.

I wish I could. It's in build phase slated for late Q4 release. Great counterpoints, btw.