If the July demo is going to be similar to the GT5 demo for the second GT Academy, then I expect it to just contain the Academy combo (wouldn't be surprised if it was multiple Nissan cars) - or something that you have to continually update via small downloads if they're going the multi-stage route like last time.
I would certainly expect it to be much-updated build, something they are happy for people to have on their home consoiles as a good representation of the product, compared to a build being updated up to the last second meant only to be experienced for a handful of hours at an event and then taken away and not left in anyone's hands.
I'd be very surprised if they included anything other than Nissans in the downloadable demo, especially if the sole purpose of that demo is to co-promote the Nissan GT Academy and drum up interest in the upcoming GT6. It's still quite well-remembered by the PR group handling GT Academy in the UK that the GT5 demo had 2 million downloads, and I had expressed my opinion to them that those massive numbers at the time had a lot to do with people wanting an opportunity to test out GT5 physics as opposed to being directly interested in the Academy (obviously they would have come to the same conclusion by themselves without my input).
I'd be surprised if they didn't include a Silverstone configuration in the demo, they often have wanted to put people on combos that were unfamiliar to all generally - be it Indy or the Eifel created tracks.
Regarding FFB, I'd find this a little hard to answer because I'm personally quite sensitive to hardware changes, so running at these events on the Thrustmaster wheels is immediately different for me compared to the G27 I use at home. I drive almost exclusively with FFB set to 1 on my home setup, so I may not be the best judge of this parameter. Also, I almost always find it harder to catch slides and spins on the Thrustmaster wheels than the Logitech ones. Having said that, I think my initial difficulty in finding the limit was a lot more down to unfamiliarity with the International layout at Silverstone because both Alex and I were able to push boundaries in cars and corners quite well after the initial time spent on the demo.
I found the racing hard tyres a bit more challenging than before, and the lower grip comforts and sports I really enjoyed. The Dino and Countach were so obviously different with the Countach's understeer on entry quite different to the Dino's more slidy and delightful manageable oversteer. I could feel more grip sensations - that's not to say there was MORE grip - I could just sense more, but making some kind of sense of that and manipulating it would probably take me some getting used to.
What is it specifically that you found iffy about low speed physics in GT5? Maybe if you can elaborate a bit more on the specific issues I can give some input. From my own memory and experience, I didn't have any bad feelings about the low speed GT5 physics.
I didn't run any FWD cars sadly, just the Countach, Dino, SLS GT3, Nurb GTR and 370Z, also didn't try any standing starts. I just fell into the regrettable WRS-running habit of ghost-chasing, lap-time chasing and restarting after a poor 1st corner
All the best
Maz