I never built it but i did study that site before i built my own speakercab. Reasons: that speaker is no longer made and 114 liters of internal volume makes it a rather big 1x15 (but apparently that speaker needs this much volume).
Other than those things this is a solid design.
I ended up building a 2x12 using Eminence Delta 12LF speakers. It sounds excellent, but a recent change in my taste has me lusting for some tweeters so on the drawing board are now 2 1x12's with tweeters using the same Delta 12LF's. That way i have a more modular rig wich is easier to carry and i have my tweeters.