Ok... My opinion from working in a baby store...

The SNS Plaitnum, is great and should only be about $20 more than the Meridian. They have exactly the same features as in the Active Head Restraint (AHR) which moves up as bub grows bigger. The Plaitnum boasts a few 'extra' features, inlcuding a seat belt lock off, speakers in the AHR that you can plug in a portable listening device for bub to listen too, it also comes with a full length car seat saver, which covers the back and seat of your car seat.

I would whole heartedly agree with the manual system as you are in control at all times, the retractor system tends to lock off as soon as it hits something so if bubs has a bigger jacket on, you may have to re-adjust the belt anyway.

HTH