Fab idea. Heard of them before (ages ago). Good to see they're still at it.
Been and had a play today. Brain dump follows.
In all cases I tried the cameras with at least two lenses (kit + at least 250mm zoom).
First camera shop (T4 Newbury): Tried Canon 1000D and 450D vs Nikon D60 vs Pentax K-m.
They don't stock the Sonys (told me they did stock them but didn't rate the build quality and stopped).
Of those, I found them all acceptable but found the status line on the Canon 1000D/450D easiest to read. Handling seemed OK on all of them but to be honest I don't know what I'm doing yet so undoubtedly held them all wrong. I'll learn. I took an SD card in with me and left with photos taken with the 450D to drool over.
Pentax K-m is an interesting beast. It's by far the cheapest (comparable with the A200), but lacks Live View. I've read reviews which said it was a good camera seriously let down by a couple of issues. I'd certainly like to hear real-world thoughts from anyone who has one though because the price is so keen.
Nikon D60 is a good contender but price is comparable to the Canon and it has the lack of in-body AF motor to deal with. Probably going to let this one go.
As it happens, they also recommended the Canon 450D for the Airshow work. £810-ish new for 450D + 18-55 IS + 55-250 IS + UV filters for both lenses. Also tried it with a 70-300 Sigma, but it's non IS, and I'm not the most stable so IS seems a good idea (the 70-300 IS Canon puts me over budget, but may be a 2nd hand option). Credit where it's due - they know their stuff and seem to be competitive on price.
Second camera shop (Jessops Newbury): Tried Sony A300 vs Canon 1000D
Unfortunately, the shop was suffering from a power cut at the time and the battery in the Sony was showing 6% remaining so my options were limited. The sales guy was singing the praises of the Sony (bigger grip than the Canon, and I can't deny that one). I actually hurt myself gripping the Canon, but probably holding it wrong. I noticed some give in the Sony grip too.
I need to go back and try these again when they have power because I want to compare Live View options. They put the Sony 70-300 G SSM on for me but with the dead battery I didn't get to use it. My god it's heavy though. They tried to explain the difference between that and the cheaper lenses but I got blinded with camera-speak.
As noted above, I'm going to go back and try all the cameras again once I know my budget for sure. Since I'm not entirely sure what I'm doing are there any good buying guides for SLRs? I'd also appreciate comments on the above (either agree or disagree).
Thanks all for your continuing help and patience. Signed, one very appreciative newbie.