I’ve been on the combo for around 18 months & I’m generally happy with it, I don’t find the problems linked above anywhere near as bad as they’re made out to be but the way it calculates IOB does have some quirks but you get used to them pretty quickly.
I notice & have problems with it most if I manually enter a bolus on the pump as it insists there’s a whack of insulin still working & the adviser won’t give corrections till its used up. I think the way it calculates IOB would be more of a problem if you move from one pump to another but the advisers all work differently.
Personally my my hba1c was around 10 before going onto the pump and my last two readings over 6 months were 6.2 and 6.3, without hypo incidents, so whilst some of the things bug me its gotta be doing something correctly!
I’m aware of one or two other combo users on here who may be able to give other insights & I recommend Alison &tims links as well as suggesting you get a copy of pumping insulin by john Walsh, its quite heavy going in places in that you’ll probably only realise a great suggestion the 3rd time you read it but it is a bible & mine of great info.