I ended up getting the ARB twin compressor installed under the hood this morning. It wasn't the worst of installs but it was time consuming, tedious and my hands simply don't fit in the areas they needed to be in. Bolting the Slee bracket down once the compressor is installed to the plate is definitely a test of ones patience and ability to finagle their hands into an odd space while attempting to almost blindly thread a bolt. I had originally planned to run it to the Switch Pros 9100, but I haven't gotten around to installing that yet and I am waiting for a few more lights and a winch/bumper before I go through all of that. For now I have it wired to a AOB compressor switch that fits in a button blank on the lower left kick panel. So far I am pretty impressed, I took my tires down to 20 PSI today on the beach and then aired them back up to 38 PSI before heading home. It took approximately 25-30 seconds for the compressor to put 18 PSI in each of the 275/70/17's (32.5's), not bad if you ask me and certainly faster than the typical gas station air compressor. I am sure that it would be two minutes plus to take a 37 from 20 PSI to 40+ PSI and you would likely need to give the compressor a break for a few minutes to cool down half way through. The compressor was certainly warm after consecutively airing up all four tires but it wasn't to a degree that one should be concerned.
I have run Power Tanks, ViaAir compressors, and York OnBoardAir systems in the past and they all have their strengths, but for the size of tires that the 4Runner will ever have fitted (34" max), this unit is more than adequate. I can see it coming in handy to blow off the rear window as well as airing up air mattresses and possibly some light air tools although a tank would certainly help with the tools. After buying the compressor at a discount, the mounting bracket, air inflation kit (needed for the QR chuck), AOB switch, and the ARB digital air inflation tool/gauge (very nice item BTW), I have just over $650 invested in this setup. It's definitely not a cheap accessory, but I think it will pay off in the long run and should I ever decide to run a front air locker all I will need to add is the manifold ($70) and I'll be in business.