If you want a clear case and already have a Seidio one (and assuming you like it), why not get the Crystal or Hybrid case from Seidio? You probably already have a skinned holster to hold it, plus you already know what the quality is like. The one negative I think to the Speck case is the cheaper plastic and (if I remember correctly) the holster doesn't have a magnetic sensor, so it doesn't go into 'holster mode'.
Personally, I have the hybrid case and I like it. However in the future, I may get one that isn't clear. I get a ton of dust and stuff stuck underneath, which you can see since it's clear... which isn't cool. I'd clean it, but I haven't taken the case off since I've gotten it and really don't want to (for fear of making it loose or something). Just something to think about too.
