I have AND 1.70 can i upgrade it to 1.71 or do i have to do a clean install.
Also will I have to start a new game?

I tried upgrading from 1.70 to 1.71 and I got some critical errors, so just now I tried again with a fresh 2.9 ROM and so far, so good.
Aff said they would break saves in the thread at the top

Oh i wasn't aware, thanks!
It seems like the thread is just edited so i don't know if the numbers are changed or if the other details were edited aswell