Hehe, looks like ludi has some Tokina love going on (together with your recent 12-24/4 acquisition)
Agree that it's a bit soft at 200mm @ f/2.8, but it sharpens up respectably by f/4, and the softness will probably not be detrimental when shooting portraiture. I imagine it's also a lot sharper at 150mm and below.
What's the bokeh like? Some lenses struggle with this
despite otherwise respectable characteristics.
A word of caution from someone who's been there - it's very tempting to get better and faster lenses, but I found that as my lenses became bigger and bulkier, I started carrying my camera out less and less until I stopped doing so altogether
Finally, the straw broke the camel's back, and I retired my 40D and L lenses in favour of Micro Four Thirds. Definitely not the path I'd advise for everyone, but it's worked out well for me so far. Now I just have to be careful not to replicate my mistakes with the new format (lusting after that Voigtlander Nokton 50/1.1 atm*...).
*It's bigger, but no heavier than my current SMC Takumar 50/1.4 + M42 adapter
BTW, Got to play with the Tokina 11-16/2.8 the other day, but as I didn't bring my Canon body, don't have any samples to show. Build quality is pretty good (about on par with Sigma's EX line), and it has a clutch AF/MF mechanism similar to some Tamrons (probably useless on an ultra wide). It's got pretty good distortion and resolution
as long as you don't mind correcting CA in post (which, if you use Lightroom, you can probably automate with lens profiles).
Wind, Sand and Stars.