Contol upgrades--which are worth it?

Littlelandlord

After Hurricane Sandy, I replaced three flooded boilers in my three unit 2200 sq ft apartment building on Long Island's south shore with an old-style 52KBTU output New Yorker atmospheric boiler, complete with standing pilot and power vent damper (got it cheap and new). Used three zone valves with a Taco ZVC controller and allowed the tenants to continue to control their own temperature. Also replaced three water heaters with a single unit. I figured I would put in three new condensing boilers when things settled down.

Here we are almost two heating seasons later, and I'm averaging $100-110 per month in gas, heat and hot water. for the entire building. I'm billing a tad more in rent and as several Wall contributors suggested after Sandy, separate heating systems just don't seem to make much sense for this building. Also suspect that a new condensing boiler wouldn't pay for itself either.

So the question is, is it worth bothering with additional controls? Some options I'm looking at:

Outdoor reset. Taco FuelMizer is cheap and stupid easy to install with the TACO zone control.

Variable speed pump. Taco Bumblebee interests me because of low electrical consumption. Not sure how much electricity I would conserve, but it appear to be a better fit for standby power. I've operated the boiler on battery already, got about 8 hours on a 32 degree day, and the Bumblebee should be good for three or more times longer.

Purge/post purge/pump exercising. Probably overkill but the New York originally had a 30 second purge cycle, which was disabled when the zone valves were installed. This seems pretty hard to implement.

Besides the usual Taco stuff, I'm also looking at the Honeywell AQ250 boiler controls, matching thermostats, and outdoor reset module. Sounds a bit more sophisticated than Taco's comparable units, and not quite as complicated as Techmar.

Oh, almost forgot, probably a mixing valve for the water heater.

I will likely wire all this myself, and have my electrician check my work as part of a bigger job he's doing over the summer, so I'm basically paying for materials.

Thoughts?