UA is better value, the only thing that should swing you is storage (as you mentioned) the value of accessories such as child seat, canopy etc. and overall weight, I think UA is 49kg.
By the time you add the cargo line motor and accessories to the UA, there's not much in it. Although, not sure what's included with the list price on Fully Charged.
Just watched a load of Packster 70 videos. Now planning the storage shed. I hate this.