I think the main problem with the "Toomer Coasters" is the way they age, not the original design. It seems that when they were designed to try to squeeze too many elements in too small an area, the coasters aged quite quickly and not very gracefully.
Look at the Arrow rides that people do most of the complaining about: Steel Phantom and Drachen Fire. Due to my relationship with Kennywood, I was one of the very first on the Phantom. I LOVED that coaster, and tracked up a couple of hundred runs on it that original year. (A friend and I were having a race.) It was fine. I was at BGW the first month or so that Drachen Fire was open. Once again, I thought that it was quite intense, but still a great thrill ride. The inversion right after the lift hill, still suspended in mid-air, is still one of my favorite elements ever.
Look at those rides a few years later, however, and it's an entirely different story. I rode the Phantom a total of ONE time in 1999. We all know what the fate of Drachen Fire has been.
I truly think that squeezing so much in to such a little place put WAY too much stress on the track, supports, rolling stock, all aspects of the ride. You can weld and weld, but you're gonna feel it. It is never the same after you have to modify a ride in any way. Strengthen something, and the force will go somewhere else.
Now consider the "other" Arrows: Magnum, PepsiMax, Loch-Ness. They have larger areas to work with, and don't try to do too much in too tight of an area. These are still great rides years later, and I feel that they will be for years to come.
Whether the blame here lies with Arrow, Ron Toomer, or the parks themselves (I know BGW was very strict with what they wanted for DF) I don't know.
You can't bash them for trying, though. Without Magnum, there's no Millennium Force. Without the Steel Phantom, no Phantom's Revenge. Without Ron Toomer, we'd all be riding Chance Toboggans.
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"Let's go out and have some fun!" (New Order)