I started responding, and found that I'd written an essay!
Yes, fewer academic awards at 11+ from W & T I'd say, though that is a continuing trend I think. There are now 420 boys grammar places, so a lot of competition there. More academic awards at 10+ and 13+ Numbers of applicants up at all schools, but lots are sitting more schools than ever before.
In terms of how the exams have changed: The final Wilson's score is based 40% on their creative writing task for next year, so that will be a key area. If you have someone who is reasonable for maths, but who can write well, then you have a very good chance of a Sutton grammar place, whereas I think that the Trinity exams possibly still suit mathematicians who are weaker on English (given the verbal reasoning papers contains codes etc, and say up to half the paper is technique rather than vocabulary driven). Whitgift entrance is a different matter - this one is still very much looking at the whole boy to see what they can work with. If your son is particularly "lopsided" or quirky in terms of ability then I think W gives him the best chance of a place. I think to have a chance of a bursary you have to be at scholarship level, and I know prep boys heading to Wilsons as they only got full fee offers from W & T. Which will have a knock on effect at Wilsons especially on the co-curricular.
In terms of preparation - no one is going in unprepared these days. The Sutton Grammar PTA mocks will give you an initial idea as to where your son sits within the cohort for the year. But it is a numbers game in part - 420 boys grammar places, 100 or so 11+ at W, 70 at T, 20-30 at C - those are good odds to be honest (unless you have a very strong preference for co-ed.....). For the indies I think that the threshold for getting a place was highest at T. C always has a wider range of ability due to their prep school pupils not having to compete at 11+, but there were a number of external siblings who didn't get an offer this year. I don't know of any full feepayer not getting into W at 11+ this year, but other posters do, so they may have a better view of where the threshold was. If you definitely want W or T then I think 10+ is possibly the best option - the scholarships aren't as big but there seem to be more of them, and you can get bursaries without the same level of competition? Though I guess it may still work out that you're simply getting 8 years for the price of 7...