I run a blitz dsbc, (its what they call the sbc spec R now.)
Its fine to use, and produces stable boost for me, right up to 23psi. It will control actuators (as on std turbos) or wastegates if anyone has gone that far with aftermarket turbos.
The unit itself is said to handle up to 36psi boost.
My understanding of the advantage of dual solenoids over a single is that they can effectively 'pulse' twice as fast, meaning it gives a smoother curve.
It doesnt lose its settings when you you disconnect the battery, and you can control the rate of boost increase as well as the ultimate boost pressure. Some ebc's do this, some dont. It has all the usual warning features like it beeps if you exceed a set boost limit, and you can program it to reduce boost by a % if you do exceed that value. Lots of other ebc's do that too.
When i was getting it i was choosing between a Greddy, the Apexi avc-r and the Blitz. I went for the blitz because it offers direct control, ie i can define what i want to happen, it doesnt depend on a 'self learnt boost curve' as many of the Greddy units do, and although the apexi offers lots of cool features i really liked (eg boost variable by gear etc) it had a reputaion for spiking. The dsbc had a reputaion for a smooth curve (said to be due to the dual solenoids and hence faster pulsing) and higher boost capabilities as well as offering the warning/saftey capabilities.
Cheers,
Ben.