To Andy the original poster. I think your linked new test stand is superbly well built and very well thought out with the ability to do beam and radial mounts with such alacrity. worth every penny and I certainly would not mind having a pair.

I have made do with a variety of test stands some commercial and some just home made . Here are five of them currently in my shop unfortunately in the past I have let some go.

Now I do agree some do overstate the need for a good stand particularly when we are talking about new folks and using superb modern new engines such as the OS AX series which indeed shine when just installed and running a tank or two then flying. Thats what those engines do so well.

However there are a number of other reasons to own at least one stand and that has nothing to do with 'pure racing engines'. Probably the most important may be simply when we want to work with an unknown engine, Or just an engine that may be unknown to us. A good test stand is the best way to learn a new engine that is new to us. This especially so for example when we want to learn an engine that may be outside our normal scope such as a diesel or maybe a rotary or heck even an RCV type, maybe even a little retro and learn operating a vintage sparker. Doing any of this there is no better way than a test stand, true while the stand may not replicate the exact installed conditions (cooling, engine orientation fuel supply etc.) but so what the stand is the best place to start.

Now there is another reason and while its not as often mentioned, this activity is multi engine flying. One of my favorite activities, I have produced I think around sixteen ships now which includes twos, threes, four and even a six engined ship most pretty darn successful and a few were not.

Anyway I always cringed when I hear someone say "I got an old fill in the blank engine and can I just buy a new one for the other side".
To me old unknown or otherwise junk engines belong on single engine airplanes and for the multi's I always purchased new. Now and here is where I have received a lot of heat over the years but could care less as the success bears me out. For all the multis I always break in on test stands and at the same time on multiple stands regardless of the number of engines. The Six Pack was a challenge

John