I have an 11 on the MTB and an 8 on the commuter (which i’ve had for about 1000 miles longer).
i ran 1×9 prior to having the alfine on the mtb so didnt miss the spread of gears (it was an improvment over the 1×9 setup). i run 32 x 20 now as that seems to provide a similar spead to running a standard double ring (22,32 x 9speed).
it doesnt take any getting used to really, but i would try running your bike atleast without the big ring 1st.
As for being heavy on the back, yes it is, but imo the good points out weigh the bad. They do take a bit of setting up though – but once dialled in they stay pretty much maintainance free for a good 1000 miles or so.