A better option to an expensive watch as a backup computer is the Deep6 Excursion computer. It will most likely go on sale later this year for $300 (normally $350) and runs a full Buhlman-16C with adjustable gradient factorsthanks, all for the input. The consensus seems to be a second computer is better. I currently use GF 40/85 for my peregrine - which is the default. So I think the best way forward is finding a computer with the same algorithm so I don’t have different NDL/deco measurements. Will wait for a sale and maybe get another shearwater. And maybe till then add an analog depth gauge to my SPG.