I have a couple of questions/suggestions :

Runes & Masteries : I would use Cooldown Reduction Glyphs and switch those 4 points in ALACRITY over to SORCERY seeing as Cooldown Redction is really important for Ashe ESPECIALLY after the recent nerf to her Ultimate's Cooldown. I would turn the Seals into Flat Mana Regen. And swap those 3 AP Quints with some Armor Pen ones. '

Basically the AP you are trying to get with the Quints and the 3/3 in Archmages Savvy will do absolutely nothing to anyone, especially if you dont have the 1 point in 15% magic pen.

Take the 3 points out of increased armor thing, put them into the increased EXP thing ( very good talent) and the remaining point into MP5.

As for itemization, you should always, ALWAYS keep the boots. Do not sell them for another PD, you will lose alot of valuable MS.

Basically if you reach end game with this build, seeing as you have almost no armor penetration, you will be very easily countered. I suggest ( along with the runes i mentioned) that you smack either a Last Whisper or a Black Cleaver somewhere in your build.

Lastly... 3 Bloodthirsters? :P I would put a Banshee's or even a Warmogs instead of one of the BT's

Anywhoo, this is just what I think. If this build better suits your style of play, then dont listen to me :P