a big concern i have is the longevity of all the electronics such as the nanny and dess etc. If those fail what can be done?
I think the big thing is "IF" those fail. The only electronic component on the F3 lineup with a greater than average failure rate that I'm aware is the DESS module. I did replace mine on my 2015 - $150 and easy DIY repair. That said, now that I have BUDS, I'm going to just disable the DESS altogether.
In the event the electronics fail - and I"m not hearing about any others having major issues - you can replace them - nothing major has changed on the F3 lineup since it came out - so even the 2015s which are now 8+ years old can get parts for since they share parts with the new ones. Dash is different - but I bet a new dash could be fitted to an old machine if necessary. If not - there are still old dashes out there.
I guess what I'm saying is - me personally, I'm not worried about failing electronics on the older F3 models at all.