radiant heat source to replace Bock water heater?

Hello all.

I self-installed a 3 zone closed-loop system of 2 floors of radiant and one floor of hydronic radiators about 12 years ago in my small (500 sf/floor = 1500 sf) NYC home. The whole thing has been powered by a 50 gallon oil-fired Bock water heater with no issues for all these years. (Well, one day when it was unusually cold, like -15 degrees F, it had a tough time keeping the house warm). The basement has pex in the well-insulated concrete slab. The 1st floor is staple up under hard wood floor, and the top floor has 3 radiators and one towel warmer (run off the 1st floor loop).

Insulation upgraded in the attic, but the walls are still balloon-frame without any real insulation on front and back, attached on one side. I calculate my heat loss at about 45,000.

I came home one day to a bad smell that was coming from the oil burner / Bock water heater. It turns out the combustion chamber has become very charred and the insulation had burned. I shut everything off --it looked like a serious fire hazard. I'm now at the point where it certainly appears the water heater needs to be replaced and the venting re-done. Bad soot buildup in the pipe.

I know technologies have now changed and I want to ask you all what sort of replacement I should be looking into?

My fuel options are:
1. Continue to use oil (I get B20 delivered and my tank is squeaky clean from the 10 years of this). This would be easiest.
2. Upgrade electrical panel to the house so as to accommodate an on-demand self-modulating electric water heater like the ecosmart or the seisco which both appear to be approved for use in radiant heat. Panel is 100amps at present, so I don't think it could handle it.
3. Convert to gas (would require running a new gas pipe from the meter); mine is 3/4" and already has the stovetop, dryer, and domestic water heater running off it.

My thoughts are perhaps a high-efficiency condensing oil-fired boiler, maybe to also handle hot water and get rid of my gas water heater? Not sure if those would be able to heat water for the closed-loop system and also for the domestic water? I'm unclear if those two water sources mix? I looked at some fancy expensive ones, like the energy kinetics and peerless and some other more common ones, but I don't know what the best and easiest would be for my system.

I'm intrigued by the electric as well --haven't figured out if it would be more or less expensive for me, but I like the simplicity of it and the tiny space it would take up. And no venting. Could get rid of the oil tank, too. But I know this would require permits, etc. and it's a little cold now and just before the holidays. I sort of need a quicker fix.

Gas is the least exciting to me, both because it would also require a permit and running a new pipe through my recently finished basement ceiling does not sound like fun. I also just didn't like the guy who came to try and sell it to me. I was hoping for a knowledgable oil person and he faked his understanding of oil and pushed the gas option. He also offered to just replace the Bock, but clearly knew nothing about tuning a burner or doing the venting. So why would I have him do it? The argument in favor of gas is that everyone knows how to service it (more or less) and the venting is pretty straightforward.

Thanks in advance for any help. Please if you can offer specific brands/features to be on the lookout for, that would be helpful. I've become distrustful of many of the installers who seem to just sell what they know and don't take the whole picture into account. So, my solution is to figure out what I want first and then find the right person to do the job correctly based on that. I'd be happy to take advice on reliable, fair, smart NYC-based installers.

Thanks!