Fast af "normal" zoom for my brand new k20d :D

Hello everyone
i just received my new k20d + 18-250 and tumax flash ( won on ebay ) and cause i sold my dear k10d + kit ( AL II ), now i'm gonna rebuild my "normal" park of lenses.
The idea is to sell the 18-250 ( already in lot of forums/places ) because i have no use of it ( i'm already covered from 50 of excellent glasses ^^ ) and to buy a very fast af zoom.
After seeing a lot of reviews and opinions, the list ( by preference ) is:
1. Sigma 24-60 f2.8 - Sharper than 24-70 sigma and wide enough to be a good Permanent lens on the k20d body. It's my best choice because it has a very good range (24 is enough for me in the wide side for the permanent zoom), it's sharp from TA and it's price is wonderfull (or not ? Oo)
2. Pentax 17-70 f4 - It's on second place just because of the sdm fails... I want to buy this objects "used", so no warranty ecc... If sdm fails i'm F****D
I would love a non sdm 17-70... this range is fantastic and i don't care about the TA f4 instead of f2.8
3. Tamron 28-75 f2.8 - Sharp from TA but there are 4 mm less then the sigma. If i buy it i have to take also a "wide" prime. More expensive than the sigma
4. Pentax 16-45 f4 - Nothing to say... good enough but not "fast" enough to be my favourite choice. The range also is good but i would prefer some mm more then 45 :
5. Tamron/sigma 18-50 ( or 17-50 ) f2.8. I saw some opinions saying "sharper from TA" and others "sharp from 5.6"... I think those lenses had discontinous production.

Sorry for my bad english... i'm out of training ^^
Have you anything to add to my personal list ? I'm searching and i'll search for weeks... Best price will win.

P.S. i know the 24-90 pentax, but i don't like his structure and mechanical

Your wish-list is a little inconsistent. You say that the 17-70 is OK, but the 16-45 is too slow. Yet both have a maximum aperture of f4.

The Sigma 24-60 is a poor range for a DSLR, especially considering that you say 17-70 is "fantastic".

You haven't mentioned the obvious choice - the Pentax 16-50. It has a good range (not quite as good as 17-70), is optically very good, and is both fast and weather-sealed. It is, of course, not cheap.

Don't be too put off by the talk of SDM failures. As usual, a few failures have received a lot of publicity.

G

What does TA mean?

I find your list also a bit strange, it seems like a DA40mm would be your best choice since it's cheap very sharp wide open and it's precisely in the focal ranges you mentioned. Just step forward or backward to zoom

Eheh
right... i didn't specified why i wrote that list and why i said 16-45 is slow..
17-70 is a fantastic combo because it has a very perfect range ... who cares then if it's f4 ?
f4 is not fast as 2.8 but it's fast enough if the focal range is 17-70 ^^ no ?
I said 16-45 is not fast enought for this reason.

TA = max aperture... i don't know if ta is just in italian... xD

And... no, 16-50 f2.8 is not a good choice... well... if you know somebody who sells it for 350€... ok !!!! ahahhaah

My Dad has a Sigma 24-60 2.8 and I must say it's excellent. If you're not bothered about the wide end, it's a gem, very good from wide open at all focal lengths.