I've tried most of the glycin devs., including Agfa 8, Edwal 12, 777, etc., and I haven't been able to get the magic out of them that others report.
I have mixed these devs correctly, followed times found on APUG and at other sources, but my highlights keep buring out. I've tried cutting back on times and/or number of inversions, but to find no improvement.
I'm saving my glycin for Ansco 130, a print dev., where I think it really shines.
Now, just because these glycin devs haven't worked for me doesn't mean the same for you.
I believe Tom Hoskinson is an Agfa 8 user; take all the advice he can give you.