7D w / 35-350

Does the MA help on the 35-350 ?
right now between 35 to about 50 mm and above 300 mm seems soft to me .

MA might possibly help, but I can see how adjusting for one end of the zoom might mess with the other, especially since it has such a large range. Also, you're critiquing the very extreme ends of the lens' range where it might not perform best anyway.

You are putting a necessarily quality-limited lens (the natural trade-off for such a huge zoom range) on a camera that is known for demanding good glass.

So , I would be better off looking at the 100-400 IS ? If I go for the new 70-200 II [almost get the 100-400 IS and 7D for same price] I would have to carry the life size converter also to get out there .
Cost is about the same [7D and 100-400 IS] . The cost of the 100-400 IS might go down , where I know the cost of 7D will .
I carry my 10-22 and 17-55 right now . If I go for the 100-400 IS or 70-200 , all my lenses will take 77 mm filters . Right now I have to carry extra ones [filters] for the 35-350 [72 mm] or 28-135 is also a 72 mm but it is not short or long enough .
Right now I am pretty will covered from 10 mm to about 300 mm with 3 lens .
If I go for either the 100-400 or the 70-200 , there will be a gap - small between 55 and 70 , a little bigger from 55 to 100 .
I know this is my choice and my own opinion is buy the best glass you can afford .
I was really hoping someone had the 7D and 35-350 combo and could say yes ,the 7D makes a big difference or no , the lens is just bad at extremes .

I guess I didn't realize this was an L lens. No surprise though that it is not razor sharp all the way from 35-350 - that is a huge range. Sounds sharp from 50-300 though - if I were you I would consider the lens a 50-300 lens and just avoid the extremes.

I have the 70-200 2.8 IS Mk I and I absolutely love it. Combined with the 18 MP of the 7D, you can crop in pretty tight and still have clear pictures.