I am currently running a frankenbrewed 3bbl electric brewery. I have no real problems with it except having to clean the elements. If one of the elements crusts up it can burn and ruin a batch so the cleaning regimen is essential. there are reports out there that say that electric elements can give an odd "grassy" like flavor to bittering hops so some people bag them, but I have never had this issue and I use pellets directly in the boil. Electric is also quiet, which is really nice.
Anything larger that a 7 bbl system and you pretty much need to go with direct fire or steam.
We are in the process of building a 10 bbl brewhouse and we looked at going with steam jacket. Steam gives a more even heat and doesn't scorch as much on the bottom of the kettle making clean up easy. Steam is also quiet since you will have the boiler located in a separate sealed off room.
The problem is the boiler, you are going to spend at least $30K to have a boiler installed and they have to be maintained constantly. You have to have an RO system to feed the water into the boiler to keep the coils from calcifying. You have to have it state inspected. We just weren't ready for all of that and the additional 30K was going to put us over our budget so we went with direct fire. I also bet your "turn key" system doesn't include a boiler.
On our next system we will go with steam, but direct fire is easier to install and mostly maintenance free except for cleaning. It also ended up being cheaper to just run larger ID gas piping over to brewhouse than to run more electric, and we will need the electricity we currently have near brew house for keg cleaner and pump, and small electric pilot system.
So, I would say if you are going 3 bbl go with electric. 7 bbl it is a toss up between electric and gas, depends on your building requirements. If you can afford steam and are ready for a bit of a learning curve it is probably the best option as far as efficiency goes.