draw biased driver vs adjustable driver

I unfortunately can't speak directly to your question, as I have never used an adjustable driver.  I can just tell you anecdotally, that I have used two types of Draw-biased drivers.  One was a TM '07 Burner Draw that I do not believe has any special weighting to fight a fade/slice, but that has a very closed face.  The other is a Ping G15 Draw that sits square or close to square, but has internal weighting to help fight a fade/slice.

In my usage, I had a horrible slice with the Burner Draw, I believe because I was overcompensating for the extremely closed face.  It just didn't work out for me.  On the other hand, I have had a good experience with the G15 Draw, and I like the fact the face sits pretty square, and that the draw bias is essentially invisible to me.  So I just play it normally and hit the ball straighter.

I think, but am not sure, that the K15 is sort of the unofficial replacement to the G15 Draw, but I have read that the K15 does sit somewhat closed, moreso than the G15 Draw.  So this is a shot in the dark, but I would suggest that you try the G15 Draw, with the right shaft, and it just might work for you.    

get an adjustable. that way when your swing gets better you can adjust it accordingly. if you get a draw biased driver you may never fix your swing fault with that club. and if you do you might have a bad hook.

I hit a K-15 at a demo day and loved it, almost bought it on the spot.  I just couldn't drop list price on a new driver.  Ping's site says the K-15 is draw biased, (they actually call it "straight biased"), with extra weight in the heel.  I won't say anything bad about Ping, they make great stuff but I ended up with a TM R9 460.  I loved it too and the price was right.  I was intrigued by the adjustable hosel, I bought a tip from Golfsmith and put a shorter shaft in, I can adjust the loft and lie to fit my swing when it inevitably changes.  Imagine, TaylorMade, the company that puts out a new driver every other month may have built me the "last driver" I'll ever need.