Kevlar adds a very lightweight but strong layer of protection to the hulls, mostly for impact resistance.
Pentex is one of the better laminates in modern sails. Two times the stretch resistance of Dacron and slightly better UV resistance.
The bigger downhaul system makes it easier to use than a lower purchase system and may allow you to apply more downhaul because of that. One of the most important things in modern catamarans is the need and ability to depower your boat when the wind comes up so as to keep it controllable and keeping as much forward momentum as possible. Pulling the downhaul flattens the sail and spills the excess wind off of the top of the fathead sail. More downhaul = more control and faster speeds in bigger winds.
The shroud adjusters allow you to tighten or loosen your stays without having to take the pins out. This makes it much easier to adjust your rig for wind conditions, sail plan, and crew weight.
If you are going to be racing at all and you can swing it all of those options will make your boat a better investment and a better sailing craft.
Good luck,