Yes, sorry - that post was meant for another thread. I transferred it there but it has not been printed.
I mentioned elsewhere an occasion when Moss Vale installed supergrass on top of the bare sand. That improved times by the order of 0.40 to 0.50 (over the 500). I suppose it also depends on how they look after the sand/loam. If it is not on the track proper it will not get beaten down much so the purchase of the paws would be problematical. They could well slip around.
Healesville I don't know about but, again, that 300m area is subject to normal track maintenance. (Note that the record speed achieved over 300m is actually much slower than the track record speed over 350m. However, this is misleading as the former was run in 2013 and latter in 2019 - apples and oranges).
See also Horsham 410m drop-in. In that case, it was done on the recommendation of UTS but the Shep case is identical. I have no idea why placing the boxes close to the rail would help - quite the reverse - but UTS found a reason. Possibly climate change?
Somebody should be able to talk about injury type and location at Horsham as there has been plenty of racing there.
In any event, I found no problem with the old Horsham 410m start, which was well away from the rail and was itself done as part of a reconstruction project. That is now money wasted, to say nothing about the extra expense of building drop-ins and buying another tractor.
Also I recall no special commentary about the slide-in 600m start at the old Geelong circuit. Obviously, that would have involved a jump straight onto the loam.
Anyway, the interesting bit is that Italian Plastic's speed rate for 385m is actually slower than the rate of the previous (390m) record - 17.96 m/s v 18.05 m/s (for Gotta Bandit in Oct 2018). It does not sound like much but the absence of supergrass could account for something.
Bulli 400m (GBOTA) also did it for a while but dumped it and returned to fixed boxes off the track a little.
The underlying reasons for all these changes are rarely stated by authorities but that's par for the course these days.