Other than the somewhat low excursion, the driver you got here will probably outdo the kappa. It appears to simply be better built. Heavier, more effecient, more power handling, larger voice coil, will probably work in a similar sized box, although you might have some trouble getting that low end extension out of a bass reflex box because of low Q.

From the standpoint of sound quality, I would probably take this woofer over the Kappa (without looking at frequency response charts or whatever). However, in high SPL applications, the 4mm of excursion is a concern.

So I guess if this is just a casual listening speaker in your house, that's a nice driver. If you are going to be pushing them hard (like I always do) you might bottom it out easily.

Having said that, this woofer is probably pretty pricey. I'm sure you could pick up woofers with similar specs at a similar price with longer excursion.

Adam