Upgrade Lens Lens Lens...

Hi so i need a bit of pros and cons and advice on some upgrades.

Current gear:

A700 - looking to upgrade to new one comming out.

sigma 10-20mm - maybe plan to keep this for now. unless there is a prime out there that is similar range and does better.

tamron 17-50 - looking whether or not to upgrade this. what are better options, preferably sticking to 2.8

minolta 50 1.7 - thinking about selling this for 35mm 1.8 coming out because find i don't use the 50 range as often.

tamron 90 macro - plan to keep this for now i think.

beercan 70-210 - thinking of getting the sony 70-300G to replace this

the one i'm really having trouble deciding is the tamron 17-50. is there an upgrade to image quality there from another lens? If i were to upgrade to the zeiss 24-70 would there be a huge upgrade in IQ?
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Tony Law
http://www.flickr.com/photos/23797749@N08/