I have been in the same boat for the past at least couple of years… yes, that how long it took me to locate the good deal on 2010-2013 TE in silver… and I was also looking for one without KDSS but with NAV for the reasons you stated;
From my knowledge:
1) I do not believe you will find 10-13 TE with NAV and no KDSS… maybe they exist, but I have not heard of one;
2) all 2010-13 TE will have sliding tray (which I also wanted because it makes floor flat when second row of seats are folded);
Before finding my 2013 TE I have also tried to force myself into liking the 2014 body style… and had 2016 TEP (without KDSS) for week as a loner… that was the week I realized I wouldn’t never be happy with 5th gen 4Runner road manners without KDSS… (I also did not like the vinyl seats..)
Now, I have a huge grin on my face every time I am getting behind the wheel of my 2013 TE with KDSS… yes, it is still BOF SUV, but the road manners are awesome! And I also know that I have slight advantage off road vs. stock trucks without KDSS and that is hard to beat!
Considering the reliability of KDSS as well as complexity of modern vehicles (including 4Runner), there are plenty of other things that can fail a lot more often than KDSS and will be very expensive to repair… this is just part of modern car owning experience… just the way it is;
So as far as possible future KDSS failure… I will take my chances… life is too short not to enjoy it!