Ordered a 100-400IS. Will i be dissapointed?

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Hi guys

I just made an online order for a 100-400IS. I have the 400 5.6L but i really want a zoom while taking my walks for wildlife photography.

I hear alot of reports about this lens being soft at 400mm.. but isnt this something a little more USM can fix or is the problem bigger than that?

Also.. I was thinking before ordering.. its an L-Series lens.. it cant be so bad its unusable? If i get a really soft copy wouldnt the Canon Service Center be able to calibrate it so it gets as sharp as these lenses can be?

Heres a sample of my 400 5.6L shoots. If im able to make these shoots with the zoom then i would be satisfied.. If not i guess i can return the lens and keep changing in lenses in field.

Photos @ http://www.bassel.se/photo
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Camera:
Canon 30D

Lens:
Canon 400 F/5.6L
Sigma 17-70 Macro
Tamron 1.4x Teleconverter MC4
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Canon 70-300/4-5,6 IS USM
Sigma 18-50 2.8 EX
Kitlens

P&S Camera: FinePix F11