Steve, as you know the Mitas (Barum) Brand is the tyre of choice for 99% of the world's Speedway riders so I would hazzard a guess they know a little about what works on dirt. Re the 400X18 Trials Universal I cannot speak from experience and as far as Dirt Track in Aus goes it is early days but a few guys are running around on them on moderns that are happy with them. So yes I would say they are competitive.
MX 250, No the prices are not cheaper than distibutors RRP. I dont recall anybody saying that they were a cheap tyre.
MX 250 I dont consider the RRP to be a premium price. Some might, and thats fine. Over the last few years I have been hosed off on a regular basis by guys riding on rear tyres with a RRP 40% more than the Mitas RRP and guys on rears with a RRP 20% less than the Mitas RRP. When you work that one out please let me know. Coincidently the rear tyre I had been using had a RRP of $165 and I have been happy with them.
Johnny O is right as is Graeme.
Steve do you run an 17 or 18 inch rear on the DR