You know, it's unreal how different this stuff can sound to different people. It just underscores how important it is for you to go out and listen for yourself--there's really no other way to make this decision.
That said, I have heard all 3 of these speakers and here are my impressions, for what it's worth. I couldn't disagree more with the first post. Ironically, I heard the Meadowlarks and ProAcs for the first time back to back at a dealer who happened to carry both(using Rega front end electronics). Spent a long time listening to the hot rodded Shearwaters and thought they sounded good but kind of flat and lacking dynamics. Definately NOT what I would use to listen to rock, blues, or even modern jazz. The dealer said he understood and immediately plugged in the 1.5s--much, much better in my opinion. More air, detail, clarity, with improved dynamics and transparency. Please keep in mind that this is just according to my taste/experience and your perceptions may be quite different.
For me it's a toss-up between the Soliloquys and the ProAcs. The 1.5s may be a bit more neutral and the 5.3s a bit warmer/fuller in the midrange. The 5.3s definately go deeper with their dual 5.25" mid/woofs, but their large rear port require at least a few feet of separation from the back wall or they can sound congested and/or boomy(Soliloquy offers a port plug that mitigates this limitation though). I ended up buying the 5.3s because they're at least on par with the 1.5s and cost more than $1000 less. My advice, if at all possible, try before you buy--that's the only way you know what works in your room with your equipment.
