Nice, not seen those listed as standard parts before. Not a particularly big detection volume, would be interesting to see how it fairs to small-ish variations of background counts.
The on-semi (formerly SensL) silicon photomultipliers are readily available from mouser nowadays, would of course, have to supply your own scintillator, but the prices might favor a pair stuck to a piece of plastic scint, run through a coincidence gate for better low-end signal to noise. Just thinking out loud.