if your looking at a dip tank i would always go for gas, the electric tanks dont tend to heat the water enough, and cost wise the electric tanks have emersion tank heater elements in, these use far more electricity than you would gas and not sure customers would appreciate you plugging into their mains to give the tank a heating boost?
Electric tanks are usually van mounted and you carry the solution around with you all day/week (however long you leave it between refills) not sure how good an idea this is if you were to have an accident, let alone if you had an accident with a tank full of caustic/corrosive products?
I use a standard tank and empty it after each job, using bio degreasers. I prefer to make up a new solution each time just incase customers come out to have a look (many do) then the tank is relatively clean and the solution is not too dirty.
I'm about to upgrade to a metal van mounted gas dip tank, but will continue using the bio degreasers, ive looked at the electric tanks but cant see the benefit, some may disagree with me just my opinion.
I'd be happy to offer you training and help you set up with 3 months supply of equipment if you want?