Just to be clear about the mount: There's nothing wrong with a fork mount per se. The LX200 line (GPS and classic) have been excellent photographic scopes for over a decade, and they're fork mounted. But the ETX line just isn't mechanically good enough for a 20-minute through-the-scope exposure.
As for whether the 8" Schmidt-Newt, equipped with a TeleVue Powermate, would match the 8" SCT, it depends. For deep sky, the Schmidt-Newtonian might actually give marginally better views--it is made for that specific task. For planetary work, you would need perfect collimation to compete with the SCT, and also an expensive magnifier like one of the Powermate. Most cheaper Barlows don't do a good job with the "fast" f/4 optics you would have. The SCT would probably have an edge here--it is designed to work in the f/10 range, whigh gives good magnification. On an average night you'll want 200 to 250x for planetary work. On once-a-year perfect nights, maybe 350 or 400x, and on not-so-good nights, only 150x. But the highest power you can get without a Barlow for the f/4 Schmidt-Newt is only about 125x or 130x with the Meade eyepieces. So a Powermate or excellent Barlow is a must, plus dead-on collimation.