I think different pumps suit different people. I had the MM640 for 4 years and got on really well with it, especially the predictive low glucose suspend.
I am only aware of the reservoir vents Sue mentions in relation to boluses being properly delivered, and never found they gave me any problems filling the reservoir. I certainly found them air-tight because I always filled under a slight vacuum.
I do agree about the huge number of button presses though - but that seems to be connected to FDA approval, and medical devices being designed for the hard of thinking. I just wish there was a way you could enable/disable ‘training mode’ to halve the presses and screeds of information that have to be OKd
I’m now on a Tandem TSlim, and the reservoir filling on that is a lot more fiddly than the MM640.
It’s a real shame, I think, that you can’t have a trial of a pump for a couple of weeks before committing to 4 years. It’s a big decision to take based on just a 5 minute hold and a few questions of a rep/dsn.