I have never had a homemade candi syrup that was anywhere close to what candisyrup.com does. For that beer I'd recommend D180.
1) thank you for the candi syrup recommendation - the LHBS carries D180
2) thank you for pointing me to the recipes on the candi syrup site.
I notice the Maredsous 8 recipe on candisyrup.com uses Dingemans Mout Roost 900 and Simplicity candi syrup:
10.0 Dingeman’s Belgian Pilsner
0.50 Dingeman’s Mout Roost 900
0.50 Dingeman’s Cara 8
2.00 Simplicity (Candi Syrup, Inc.)
That aligns with what BLAM says for Maredsous 8... that said I wonder if I'd be happier with the final product (even if it's less "authentic") if I used D180 and no roast malt.