Can't speak to those particular chisels, but I picked up a set of the Narex mortise chisels a while back and I like them. They don't hold an edge nearly as long as the older PEXTO and Swan pairing chisels I have, but, for the price, they are definitely worth it. If it were me, I would probably go for the premiums, as they will be more useful for dovetailing, but it depends on what you want them for.
How often do you guys replace your splinter guards? I've been using mine for a couple years and it's still fine. I mean obviously I'm not running the TS all day every day but I've given it some moderate use. Seems fine and I still don't get tearout on cross-grain ply cuts. What am I doing right?