Much more short tele. Missing on the long end wouldn't bother me much, since the lense will be more complementary than essential. I already have the FA 50mm 1.4 and will also get the DA* 50-135, (I'm shooting 80% between 50 and 100 mm ...).
I just wondered why a fast zoom is not more expensive than a less faster zoom (or does the little gain on the wide end really explain the price difference alone ?)

A lot more goes in to getting that wide so it is one factor, as is the Pentax name itself, third party lenses are usually going to be cheaper by comparison. Speed, IQ, weight, size, everything should be considered.

[axl]

I don't have any of those two. But I'll still give my opinion.
What do you want the lens for? How do you see the world? If you have "wide angle" eyes then I think 16-45 would be better (though I think 16-50 would be even better - one stop faster and extra few mm), but If you see worl in more of a "standard" view than Tamron would be better choice as it's 28 mm gives you nearly standard FOV on APS-C cameras. Both lenses are said to be excellently sharp, with good colour rendition, contrast etc...
so think and choose wisely, or get both and that's it
BR

[maryo]

Hello Maryo, I enjoy my tamron lens !

You can have a look here : Flickr: Tamron SP AF 28-75mm F/2.8 XR Di LD Aspherical (IF) Macro Group

Hi there. Amazing gallery-great shots. Thanks for help.

[audiobomber]

Some 16-45mm samples here. Picasa Web Albums - Dan - 16-45mm