Well, the biggest downside of playing an engineer is having a soldier/spy/demo wreck an operation in a few seconds that you've put several minutes into building. It's just annoying and has made me just quit the game on more than one occasion.
With the mini sentry you don't feel like you're babysitting the thing. You work together to kill targets, often enough with one being a distraction while the other gets the kills. If it dies, no biggie. If a spy saps it who cares. I try to keep a max dispenser nearby for sure, both for my benefit of filling up on metal and for team support. Running with the mini also lets you focus on teleporters and dispensers in the prep stage.
The jury is still out on this one. The crits are nice, but I feel like I waste a lot of the charges on less than optimal situations. Also, lucking out with the mini getting the kill or having it die is a little too conditional for my liking. I think I prefer the larger clips of the normal shotty just for more firepower when needed.
Gunslinger has absolutely revitalized the class for me. I haven't touched sniper in a week and he's normally my main.
