Cooshee or Mutsy Booster Seat?

My son is 21 months old and getting tired of the high chair. I am looking to get a booster seat so he can join us at the table and finally put the bulky highchair away.

I was reading some reviews on the BabySmart Cooshee Booster and the Mutsy Booster. For the most part, they both get pretty good reviews. Does anyone have these and have really good or bad experiences? I don't think that strapping him in is a must for us, but I wasn't sure if one that strapped to the chair would be better? We have padded chairs so I'm not sure that the Cooshee will stick, but it looks easier to tote along.

Any thoughts would be appreciated!! Thanks!