I'd say you weren't close enough to your target then (Anybody who has watched my Standoff videos will know I tend to fly with my fighter's nose practically touching my target's engines). Standoff is particularly difficult amongst space shooters, yes, and this is the way it was intended to be. There are plenty of threads in the forum which contain the question "shouldn't the game be a bit easier?" and the answer "No" from either Quarto or Eder. It's hardly impossible - there's no mission I've not beaten on Nightmare and I'm far from the only person who can say that. WC2, on the other hand, is particularly easy amongst space shooters.
I don't think it is particularly difficult to hit enemy fighters, even Sartha; sure, they dodge around a bit, but their evasive patterns are fairly predictable and they don't move that much either (that and you only need 2-3 solid hits to cripple a Sartha anyway).
Would I agree a shot should be faster than a missile? Eh, maybe. Shots and dumbfires travel about the same speed, I'm fine with that. Standoff dumbfires are ridiculously deadly compared to other Wing Commander games, but I quite liked having 2-4 "OK, this ship dies now" buttons.
Standoff's sheer speed gives it, in some ways, as much in common with Starlancer as it has with WC2, excepting it lacks the "fail the mission once to figure out how to beat it" mission design. I adored Starlancer (except for the mission design), and I like Standoff's difficulty, so personally I wouldn't change the flight engine at all.