I agree with advice given, but if you do decide to stick with SLS, I think it would be worth making sure you are doing everything you can to maximize your chances of meeting people you are compatible with. Your "hit rate" does seem low, even given all of the limitations of this method.
We have used an online site and, like you, do not have very much time to commit it (or to swinging unfortunately) like you, but have managed to meet quite a few couples in person, and a few have led to a couple of couples we ended up swinging. Some simple tips (you likely know most of these)
- make sure your profile has pictures of both of you
- when you describe yourself and what you are looking for, do not ben scared to be a little specific (if you only want full swap or soft swap, say so) but be positive about it. We are soft swap, but if we see a profile that says - "full swapper, don't even bother" - it turns us off. It makes you appear negative and judging
- on that note, keep your profile positive and upbeat. Sure these sites can be frustrating, but letting that frustration show on your profile makes you appear like a negative person
- when you get an email or a response, respond quickly. Swinging is not like "dating" where a little aloofness can be intriguing
- we avoid a lot of back and forth emails. We will quickly get to "if you would like to get to know us better, lets meet for a drink or coffee. We could do either X or Y evening; how about at X , downtown". This allow us to figure out quite quickly if they are serious. When we decided we did want to meet a few new couples, we committed to a setting aside two weeknights a month to getting babysitting and meeting someone for drinks. We always combined it with something else we wanted to do when we had babysitting (don't want to waste a precious night out when you have young kids) so we would meet someone for a hour and then play tennis or go out for dinner ourselves
You probably know all of this already, but if not.... hope it helps.