I've played Dually's with a ShuttleMax 9.2 and enjoyed it quite a bit...have played Streamliners and really loved them, but haven't tried one through a Dually yet. I can possibly adress a few things about each amp.
ShuttleMax- I hear a few folks say they're a bit 'sterile' and others say there's too many knobs

I don't find either of those statements valid for me. I do a lot of upright gigs, so all them bells and whistles can come in handy. They don't do grind very well in and of themselves, but I do lots of caveman, pick style electric bass stuff and can make that amp sound downright primitive. They take pedals very well too. If I had one wish for that amp, it'd be that both channels were FET.
Streamliner- I think for the size and weight, these are shocking little amps. Sounds like a nice CLEAN tube amp, to me. There have been a lot of reports of these things being tough to dial in live, to 'cut through the mix,' but there are about as many who say it's no problem at all. I happen to think the main problem folks have with amps comes when they ask the amp to be something it isn't. The couple times I played a Streamliner I was able to dial it in very quickly, and loved the sound. I have one buddy who sometimes runs an STM with a Faital loaded Dually and he likes it, so there's that
In a nutshell, the main differences between a Faital or 3015 loaded Dually, to my ears are;
The 3015's sound a little more muscular because of the mid bass hump and a somewhat aggressive 1.5k (ish) mid range.
The Faital 15PR400 goes slightly lower yet has a bit more of a 'classic' JBL vibe...smoother response from top to bottom, but not by tons.
Honestly, though I prefer the Faital by a very slight margin (this week!) I could happily gig either cab and not feel like I'm 'missing' something. For bass guitar. Upright gigs are strictly 3way cabs for me.
greenboy recently designed the 'Dually T,' which features a very high end tweeter with an Lpad if that sort of thing floats your boat...we're testing a couple different crossovers as we speak. You should be seeing the first two Dually T's coming out very soon.