I have heard of the Aerotech fin-lok system. From what I know I think it is for plastic fins and that it can be a challenge to snap in the fins. The Apogee system is for wooden fins. When I built my Torrent I put fin fillets on the outside, inside and where the fin tab meets the motor tube. That's probably why it survived a hard landing.
Yes the fin-lok system does require some brute force to seat the fins... but once they are in they are IN. Either system affords the ability to apply internal as well as external fillets... which is a beautiful thing.
You can download the assembly instructions for the Zephyr from the Apogee web site. Check it out and let me know what you think. BTW Space 1999 is on the TV. Very cheesy special effects. I never could figure out the point of that show except that Martin Landau from Mission Impossible was in it.