First off, Basal-iq and control-iq are completely different. I’m not sure if you can still get basal-iq for a tandem pump anymore. All new pumps are shipping with control-iq as of the last few weeks of January.
Users of the pump are not manipulating or compensating their settings for readings being “off”, I’ve no idea what that even means.
I suggest you reread the post you originally asked this same question about on TUD again. There’s enough info there to explain why myself, Robyn and Hammer are doing what we are and not fooling or trying to manipulate the pump in any way. Here’s the discussion about control-iq from this site:
To answer your question about a1c, it’s your decision. If you want to sugar surf at 80-90, this is not the pump for you. If you want your BG to run consistently at 110 without having to interact with the pump at all, control-iq is wonderful.
I’m guessing your on Medicare with your statement about being moved to it now. Trusting the CGM is going to be the only way for you to see your BG now anyway. Medicare has stopped coverage on test strips for anyone on a CGM starting this January, no matter what the secondary insurance says. Unless you buy strips out of pocket, the CGM is your only option to see your BG.