3S Upgrade Paths... Need SuperPINDA?  

3S Upgrade Paths... Need SuperPINDA?

I saw this post about upgrade paths to MK4 and I've been searching, but I can't find details on if I should upgrade to 3S+ (get SuperPINDA and parts) before going to 3.5S/3.9S/4S.  I'm leaning towards the 3.9S option right now as that will get me the Nextruder so I can more easily swap nozzles (been scared to do that to this point and I think my nozzle is about done).

For background, I purchased this MK3S used from a friend who upgraded to a MK4 when they came out.  I'm a casual printer, no farm or anything.  I don't get crazy with filaments, mostly PLA and PETG, but I'd like to expand to TPU and ASA at some point.  I did just buy some Marble PLA at 3DPrintopia and ran that with minimal issues.  I do not have a MMU but would like one in a couple years.  I've read elsewhere that I could likely save money by selling my MK3S and just buying a new MK4S, but that's not really something I'd like to deal with.

Thanks in advance for any thoughts or recommendations!