Yes, there are many choices out there but I believe that Spectron is the top of the line for at least Class D amps and will be for a while to come, imho. Don't know what Modwright is coming out with, and I do have a great respect for the man and company...I may get the 36.5 myself, but to come out right out of the gate with a top of the line amp that can compete with the best of them would be quite a feat.
Regarding what the upgrades do you about have it right. Like Simon told me, the stock Spectron is a Porsche, the upgraded version is a Turbocharged Porsche. You, and your wife, would love the stock Porsche. Some people though have to have the turbocharger! Like I said, it's a personal decision.
Without the the upgrades you would definitely save enough to get the LS/PS 36.5 if that is what it comes down to.