Brake pads wearing out are just a part of enjoying your Spyder!! :thumbup:
Which end wears out first is very much dependent upon how & where you ride. Now admittedly my Spyder is a 2013 RT & not an F3, but still, I do ride it fairly hard as my 'daily ride' in the local (steep & twisty) hills & also do some long & fairly fast rides here in Oz, resulting in my first set of front pads being worn out at about 12,000 km, with the rear pads lasting about 16,000 km before needing replacing. The second set of front pads lasted a little longer than the first, but I recently fitted my third set of front pads & yet I'm still only on my second set of rears....
As to why this can vary so much between riders & conditions, you need to remember that even if you don't notice it happening, the 'Nanny' is going to be doing her thing every single time you apply the brakes - that's part of what Electronic Brake Distribution means & does! EBD works tirelessly to make sure that your braking is as effective as it can be, & to do this it adjusts the application effort on each disc according to how hard/fast you've hit the pedal & the info being fed back from the wheel sensors & all the other stability sensors on your Spyder, all of which means the 'Nanny' applies the brakes most on whichever brake/disc needs it most to slow you down in straight line (or by matching your steering input thru a curve) & in a direct proportion to how hard you've stood on the pedal. So if you are riding your Spyder hard & trying to go faster by braking later & harder before a corner, then yeah, your front pads will wear out quicker just like yours (& mine) have!!
I'm pretty sure that if you were riding your Spyder gentler & slower, braking gently & much earlier before corners, & never trailing your brake thru a turn or ever giving the brakes a hard stab to correct your line as you change direction from one turn to the next will almost certainly see your brake pads all round last longer. And if you do that, then because you will have maximised the distance your brakes get to work at slowing you down & minimised the need for more effort to be directed by the EBD & the Nanny into front end braking, then your rear pads will probably do proportionally more of the work. Since there's just one set of them vs the two discs & sets of pads up front, that means the rear pads are likely to wear quicker under those conditions.... But just between you'n me, where's the fun in that!!
Enjoy!! :2thumbs: