I did have an electric HLT/HERMS heat exchanger and a gas kettle.
I now have an electric HLT, separate electric heat exchanger and electric kettle. All are fitted with 3.6kW elements.
I think that the gas kettles are very lossy compared to an emersed element. All the heat from the element goes straight into the wort in the kettle, as opposed to a gas kettle that directly heats a lot of the air and metal around the kettle. My kettle is insulated and is only slightly warm to touch on the outside; I am looking at getting all vessels insulated by a wine tank insulating company up here in Irymple.
The HLT and Heat-EX are controlled by PID temperature controllers, the kettle is controlled by a sutronics burst fire controller (manual boil control)
Electric elements are a lot easier to automate and fine tune for maximum power efficiency.
A simple timer heats the HLT during off peak tariff, and then once at temperature a solenoid opens fills the mash/lauter tun to the preset height then refills and heats to strike. Once full this then activates the power to the recirculation and step mash program (march pump and heat-ex), when ready and although I could automate it, I then manually empty the tun to kettle, flood and recirculate and empty until I am happy with SG and volume. The kettle is then brought to a boil at maximum power - 3.6kW. Once at a rolling boil the power is turned down to rolling boil (I know approximate setting from experience). A timer then runs either 60/90/120 min boil. My point is this is very hard and expensive to do with gas.
Electrics are a lot easier to protect with residual current devices etc etc. Most houses have walk up protection, I would be surprised if many gas kettle set-ups had any sort of failsafe, gas leakage detection (other than smell) etc.
I have negligible time difference getting my kettle to boil using 3.6kW compared to a gas burner (both NASA and Mongolian from G&G)
I have a young family and a sometimes demanding job so the level of automation and low cost power I can achieve using a few float switches, solenoids etc is perfect for my situation. I am up early with the young 'ens and have a brew session finished by 7am.
The amount of radiated heat from gas in my opinion was too dangerous to allow my 5 year old near the brewery to help me and answer his curiosity.
I don't need to worry about running out of gas, although if the power goes out and I need to continue the process, I need to start-up the generator which makes the whole thing expensive.
There are probably other reasons I like using electricity and some of the above reasons will not be appropriate for your situation.
I am now working on a decoction set-up on the electric brewery and that uses a gas burner under the tun to heat the thick part of the mash. The thin part gets pumped away to the kettle for safekeeping.
I also have 3 phase it's great to use if I want to do another mash whilst I have one going in the kettle- I can run all three 3.6kW elements at once, as they are pulse modulated for temperature control, they don't always draw full current and I am unlikely the have them draw full current all at the same time. Before I had a 3 phase outlet, I had a simple SSR interlock that stopped the kettle element and the combined HLT & heat-ex elements drawing power at the same time. I like 3 phase, seems like the right thing to do at these power levels.