As your complexity curve increases, your latency expectations must go down. That is what I meant when I said there is no single trading system that can be the "best".
If what you are interested in is complex decision making then it may make sense to use a different sort of messaging technology than LMAX, but you won't be getting into anything remotely "low latency". Nothing wrong with that, just needs to be a known expectation.
Yep, I've poured over the technology and concepts there and its awesome. So awesome I think you can increase complexity without too much of a latency penalty. Just behind the fast guys but way ahead of the straight algo guys is where I think the opportunities lie (I'm kind of answering your previous question about where the dials sit in my mind). I might be wrong but, and would like to test out all dial positionings at once before locking in. And that's where a flexible haskell version could shine.
I have no opinion about the choice of haskell. That said, you are already making decisions about the dials if you go in with an architecture that relies on massive concurrency, functional languages, etc. You cannot for instance get the latency dial very low with that central architecture decision.
Again there is nothing wrong with that. It's just better to state it up front as an expectation and/or a goal than to assume you are going to be able to pivot easily once you have an architecture in place.
If what you are interested in is complex decision making then it may make sense to use a different sort of messaging technology than LMAX, but you won't be getting into anything remotely "low latency". Nothing wrong with that, just needs to be a known expectation.