Also, if going back to 12.17, the usual caveats apply: that version is based on technology at least 2 years old and some users are running into website incompatibility issues (largely due to sites browser-sniffing and not supporting it in their site code - or, worse, intentionally blocking it); also, no more feature updates will ever be included in it - so what you see is all you get. As currently understood, 12.17 is free from security issues. Depending on the sites you routinely visit, you may or may not notice any compatibility problems... so, as with any potential browser-of-interest, try it out and see if it works for you.