As EMU's the 319's were 100mph units, weren't they?
So, yes a bit slower than a 387, but a bit quicker than a Turbo, although true to say we don't know what their speed will be under diesel power?
Kind of irrelevant on the North Downs anyway, as I don't think there is any linespeed above 70?
100mph yes, but very slow accelerating compared with modern electric units (though probably slightly better than a Turbo). Maximum speed on diesel is expected to be in the 90+mph area I believe, but how long it takes to get to that value remains to be seen - along with how it'll cope with accelerating on the gradients of the North Downs.