Hi. I think this suggestion was posted in an older thread, so sorry for any thread pollution.
Currently, one can navigate around the Topogun viewport using Alt+<LMB, MMB, RMB> to orbit, pan, and zoom. It would be nice to have a second optional scheme. I like Modo's scheme: Alt+LMB, Alt+Shift+LMB, Alt+Ctrl+LMB lets you orbit, pan, and zoom. It's not just that I like my program X (I'm into ZBrush more than Modo), but it does feel intuitive and has some reasoning behind it, as follows...
1. I am using a Wacom tablet with a pen. The pen is currently mapped with it's tip and two side buttons to the three mouse buttons, but it could easily not be. I think one can config the pen for new apps inside some Wacom configuration app, but it might be beneficial to consider this added user complexity.
2. My left hand (I'm right handed) is usually left posted on the keyboard, intermittently pushing alt, while I partly use my thumb on the stylus switch to control the MMB and RMB behavior. For me, it feels a little awkward to use the stylus pen in this way, particularly because I pan and zoom frequently. Now, it's not that awkward since I love my Topogun, but awkward enough to put on a wishlist. I feel that my left hand could be doing more work. I'd rather depress an Alt+Shift than use the side buttons on the pen with my thumb. The left hand is on the keyboard anyways and it just feels like a more natural gesture.
I might just be spouting off a bunch of meta-garbage, but keeping the hands busy in art apps like this seem to kind of resonate on a more subconscious level. ZBrush almost makes a kind of game out of it, where the user needs to depress a key, start moving the mouse, then optionally release the key to shunt over to some other behavior. For artists, people typically very skilled with their hands, there might be something to keeping the hands active (but not overloaded), although I'm no cognitive scientist/psychologist.
Anyways, the post is long not because I have some kind of unnatural discontent with navigating in Topogun, lol. No, I like Topogun and will continue to use the app if this is never addressed, for sure. I just wanted to provide you with some ideas and feedback to help you guys make your decisions. I love the app and can't wait to see what's to come.