We're talking in terms of propabilities here.
There is a small chance that it will last only 9 years instead of 10 (maybe there is also a chance of exploding right in someones face but it's just infinitesimal small).

My usual settings in day to day use are 850-to-125 with ULV profile.
This works stable for almost everything since I've started with it three months ago.

I had two or three crashes since then which we're caused by microB when displaying websites with heavy flash in it. Temperature is down at 15°C to 25°C.

If I remind correctly the ordering is
xlv, ulv, lv, ideal
<-- low ---------- normal --->
so try first with lv, then with ulv and when everything is stable there, try xlv.
If you're working with the kernel-power kernel (titan) the device will restore 600mhz as default after a reboot, if you haven't changed this.