I will say that I have purchased a large number of Hi-Flyers myself. I've only built one as a Hi-Flyer, and that one was built with a 13mm motor mount. Why did I buy so many of them (and continue to do so)? Two reasons - it is cheaper than any other BT-20 based rocket ($6-7 as opposed to $8-9 for a Wizard or Viking) and the body tube is a bit longer than that in the Wizard or Viking. Thus, the Hi-Flyer is really good for kit bashing into various types of contest models (18mm boost glider pods, egg-on-a-stick boosters, quick and dirty streamer duration models, etc.). Because of the price, that sucker's just a kitbasher's dream!

Greg