The SWG clearly isn't the right tool for boosting FC level quickly, and convenience is definitely the biggest benefit of having one, but from my experience, running the SWG for the extra time costs significantly less than adding bleach if the boost doesn't have to be sudden (e.g. for a SLAM). This is due largely to the fact that I purchased a 45,000 gal cell for my 18,000 gal pool, and it adds FC to my pool at a little over 0.5 PPM/hr. If cell replacement costs $1000 (which is I think is generous) and you get 10,000 hrs out of the cell (which I think is is conservative), that comes to $0.10/hr. The electricity usage for extra pump running time will vary depending on where you live and the power of your pump, but unless you live in New England or Hawaii (or Alaska, but I doubt many visitors of TFP live there), it likely won't be more than $0.15/hr. My pump is a 0.71 kW pump, and my electricity costs only $0.09/kWh, so including $0.10/hr for the cell usage, it costs me around $0.16/hr to run my SWG. For me, 10 hours of SWG run = 1 gallon of 10% bleach, which is currently $4/gal. Obviously there are many variables involved, but for me, the SWG costs almost 3 times less to add FC than bleach, and I suspect it would be similar for many, if not most SWG owners, especially if their cell is oversized.
