Kren - What you're doing is fine, but maybe a bit more trouble than it's worth. The factor to keep in mind is price point - most mixers under 10 kilobucks tend to have only mono aux sends (this is a gross generalization, so please don't flame me on it, folks!
). Most of the lower-end effect units thus only have a mono input, and stereo outs.
With the stereo input paradigm, the idea is to allow the incoming sound to be panned to one side or another, and the stereo output then follows this placement in the soundfield. While it's cool, I don't know if it's worth all the fuss, especially if the effects unit is going to be used on the auxilliary buss, and mixed into the stereo (dry) main track. Keep in mind that if the effect is being used on the aux buss, chances are you'll have the effect set 100% "wet" anyway, so who cares how the incoming dry signal is panned? Sure, there's a little more depth to the effect if stereo inputs are provided, but nothing to break a sweat about. Personally, I'd rather have a mix board with six mono sends than a mix board with three stereo sends.
Where I think it comes in handy is when the stereo signal is routed *directly* through the effect (i.e. not using the aux buss at all)... to process the entire L/R mix. In this model, it is *essential* that the effect unit have stereo inputs, because you won't be running the effect 100% "wet" - more realistically, something like 20 - 50%, unless you're after something completely outside of "normal" production values. (Again, I generalize. Sorry.)
Like I say, give me more mono sends any day - and make 'em pre-fader, so I can crank those levels!