The Narex chisels will be much better than your Buck Bros. How much better is an interesting question. I would say that there is a diminishing return on increased spending. Any decent chisel should last through a set of dovetails though.

Plane Comparison:
LV apron plane: $89, has a Norris adjuster (allows lateral adjustment), it is made from cast iron and is 5.5" long.
LN 102/103 block plane: $115, does not have a lateral adjuster, it is made from cast bronze and is 5.25" long.

Functionally the two are basically identical. Both have 1.25" blades. Neither has an adjustable mouth. Both have optional toothed blades if you needed one. Both are very nicely made and should last a lifetime or two.