You didn't say, so I'll assume you do not have any structural problems with your heart, such as an enlarged left atrium.
Was the heart surgery to correct a valve problem?
Anyway, I'd say if the above assumption is true, and I would think you doctor being willing to try another cardioversion says it is true, then go for it.
I do not have any experience with the "heavy duty" drugs, as I have refused to be take a drug that requires hospitalization for implementation. The strongest drug I've taken is Rythmol SR 425 mg twice a day. It didn't stop my AFib nor did it keep me in sinus rhythm after a electro cardioversion. I have had 4 electros, two of them put me in sinus rhythm for about 18 months each. I have an enlarged left atrium, but following my mitral valve repair in November of 2007, my heart has been shrinking back toward normal size and I am considering giving an electro cardioversion another try... and assume I'll be on propafenon or rhythmol to help keep me there. I take coumadin (warfarin) but then I am in permanent AFib... and suffer some of the same symptoms you mention... I am 70.
Do you have an internal device to restart your heart that also has a pacemaker's function with it? I'm sorry, I can't remember what it is called. My husband (also Jerry) is 65 and has chronic affibrilation after mitral valve replacement with a pig valve on Dec 24, 11. He is supposed to start on long-term Coumadin after they get done with a scan of his brain on 5/16/12 since he had a "bleeder" that resolved itself, after the valve op. He is facing his first cardioversion.
I do not have a pace maker or a defibrillator and believe neither are used to deal with AFib.
I'm surprised that your husband isn't on an anticoagulant, coumadin or warfarin. The most serious risks associated with AFib are blood clot formation, and possible stroke (thus anticoagulant - at least an aspirin) and high heart rate. My resting HR has been around 130 if I am not taking a beta blocker. I take 50 mg Metoprolol and that plus a calcium channel blocker keep my resting HR below 80, most of the time. I also take 5 mg of Warfarin and a low does aspirin each day.