I've been hunting for a Mesa PH 4x10 for quite some time and found a deal locally for a minty Megoliath at a great price, less than the max I'd shell out for a PH 4x10.
Keep in mind the PH 4x10 is my favorite cab. Just one by itself can usually meet my volume needs and the tone is what I set my standard by. The bulky dimensions and extreme weight... not an issue to me.
I am really interested in this Megoliath though. It's pristine. When I checked it out in person, I was pretty impressed by the dimensions- the thing is huge, quite deep, wider than Goliath cabs. The dual 4x10 mode on it is cool too and I'd probably find a way to use it (dual rig?

).
Based on all of the information I've been able to gather about the Megoliath, it sounds like it could get the job done for me.
I owned a GIII years ago and ended up selling it. It was nice, punchy, etc. It was on the sterile and not-so-beefy side when compared to the PH (the GIII always looked like it was going to blow up too... not good for B-range I guess). My understanding is that the Megoliath is tuned to be a little thicker and more rock-oriented in the low mids with somewhat extended lower range, so what I didn't like about the GIII might not apply. I like the idea of a cleaner/punchier 8x10 than the standard Ampeg (which is a little dark/mushy and not so detailed for my taste).
What do you guys think? Will I be happy with this cab and stop chasing after the Mesas of the past? I'd be running it with a KT-88 loaded Mesa Bass 400.