Really like it but a couple of ideas for the "wishlist":
1) A "Save As..." function would be great so I can adapt an existing diagram to a new exercise without losing the old one
2) It would be great to be able to do absolute sizing on items (e.g. make this player 4 units tall) or a "resize this to the same size as that" - I quite often find myself shrinking players, but then getting them all the same size by manually resizing them is tricky. Likewise, resizing balls manually is really tricky.
3) would like there to be some more/different types of equipment available e.g. slalom poles, pop-up goals, flattie cones/discs
3) Similarly to 1), a "Rename" function for diagrams would be handy.
5) It's great you can select groups of objects - being able to rotate/resize the group (rather than just the members of the group) would also be great - e.g. if I create a semi-circle of cones, I can select and move them as a group but if I select "Flip vertical" it turns each individual cone upside down rather than inverting the semi-circle (which is what I wanted)
Apologies if you can already do some of this stuff and I just missed it!
Great tool, though, these are just some ideas for improvements in a future version