I have never used a gas smoker, so I really can't compare, except I have used my weber gas grill and have done 11 -12 hour smokes of pork shoulder and ribs, but that doesn't really qualify although my gas grill attempts were always successful.
Electric for me was a life style choice. When I bought my MES I put a lot of hours in at work, and either on Friday night or Saturday would start smoking something. I didn't want to worry about temp, wood, I just wanted it smoke and cook the meat properly in the recommended time frames. No worry of fuel, of course had to have chips, just prep the meat, preheat the smoker, throw it in and put wood chips on once or twice per hour. I haven't had a bad cook yet. The MES just set your desired cooking temp, insert a remote probe in the meat to monitor meat temp, keep wood chips going TBS and pull the meat when done. It is so easy.
I would like a WSM, and maybe someday a real stick burner. The convenience of a well made electric smoker like a MES is hard to beat. I would recommend my 40" MES to anyone who really wants to keep it simple and enjoy great Q.
Those propane bottles need to be refilled, what does that cost $18-20+. To operate my MES is about 11 cents per hour. So about 20+ smokes to spend $18. The money I save on fuel I can buy a lot more MEAT!