hell yeah the Mids were competitive
Of course it all comes down to what part of the world u are talking about. The U.K, and most of Europe, was pretty much dominated by the Cat from about 87-92, then the Cat 2000 series took over, with the E.C version being really strong for several more years until Predator and Losi brought that to an end.
Yokomo as a brand have always struggled over in the UK from what i've read, but here in Australia they were the dominant from about 91-97, until the XX4 came on the scene.
But the Optima Mids were great race winning cars, simple, reliable, easy to drive, and even back then they were very good quality.