25F,
Can I just comment - since there seems to have been some (very interesting) thread drift here -
As a tyro (still) to aerobatics, I find another reason for not doing - or starting - aerobatics low is that it is astonishigly easy to burn off height while practicing and repeating maneouvres.
I have surprised myself a couple of times by getting so wrapped in trying to improve my rolls or loops that I've ended up much lower than I'd like to be. If you are flying something without a lot of excess power it's very easy to lose height steadily without noticing it.
No doubt the experts, like my old acquaintance Brian L will wince at the incompetence of this - but it surprised me my concentration could become so narrowly focussed.
I'd have said surprised and scared me except that it wasn't till well afterwards I had time to reflect and worry properly. At the time it was a fairly casual " Hmm - Those trees are surprisingly large" thought.
Also - it was these 'easy; maneouvres' that were the concern. I realised that maneouvres in which things were more apt to go wrong in 'interesting' ways, like flicks, got more care from me in checking height before start.
Hmm, again.