Keep the Nexstar + HC as it might be useful, and not merely as a back up if the Starsense HC ever fails. It has some diagnostic and other functions not inherent in the Starsense version. For example...
A couple of years ago, we were suffering from the 'Starsense on wedge bug' (now fixed). For some months, Celestron wouldn't acknowledge its existence. Then, I tried something a tad bizarre. I plugged in both controllers; aligned with Starsense using the ASPA routine; then compared the axis and PAE data read outs from each HC <via Menu>. This data differed, ultimately proving the existence of the 'bug'. Celestron then completely recreated the Starsense ASPA routine from the bottom up and it now works fine. There are also a number of menu functions in the Nexstar + that don't feature in the Starsense version.
I am NOT advocating anybody routinely plugs in both simultaneously, notably as if you attempted a GoTo on the second device your scope would 'lock up. Simply that on RARE occasions it might assist. For example, whilst Celestron were fixing the said 'bug' I had the fall back of the Nexstar + ASPA routine, and the Starsense HC temporarily returned to its box. I might never plug it in again, but it is reassuring to have both.
EDIT - didn't answer OP's other question.
It is vital that your Starsense HC firmware is dated 2019 or later. New devices sometimes sit on wholesaler and retailer shelves for long periods before despatch. Mine had firmware three years out of date. Prior to 2019, there were some major bug fixes. Later updates tend to me more cosmetic. But you can check on the Firmware Revision History on the Celestron website.
Edited by Noah4x4, 14 February 2020 - 01:54 PM.