I have shot both bows: 40#, 66length. Both in the GL (glass-less, carbon faced) version. The difference in limb shape is what makes the difference in performance, I think.
The Griffon is the more trad. design, has less deflex reflex and due to the trad grip design looks more like the old LB is pictured over here in Germany.
The Harrier still is no radical deflex reflex bow (is allowed under IFAA rules). It still looks like a LB, but like a more modern one with the grip set forward. So it is more like a reverse grip LB. The Harrier is also allowed under IFAA rules.
THe Griffon is a great LB (GL version). A 66" bow works well with a 27/28 inch draw, the bow has little handshock, was quite and performed like my 40# Khan RC (glass laminated) in cast, but the Khan-RC had a smoother draw and less handshock. To my finding the Griffon was more accurate than the Khan.
I was in the process of getting myself a seconbd Griffon as backup, when I shot a Harrier.
I sold my Griffon instead and yesterday my secon Harrier arrived.
The Harrier is smoother to draw, has less handshock, a better cast and outperforms both bows: my old Khan and the Griffon easily (same arrow). It is much, much more accurate due to the reverse grip. But as I have a special problem with my wrist (bowhand), other archers may not think the difference in accuracy that big as I do.