I picked up a Mega TR before xmas to replace my cracked Five (no surprised given the abuse its had).
Built it up with the same parts as my Five, apart from a reverb. (Revelations, Pro II/ZTR Flows, X9 10speed, raceface atlas bar/stem/cranks, Maxxis Minion Front/Crossmark Rear).
Mega TR feels a little bit lighter (havent had chance to weigh it yet), It certainly rides a lot lighter.
The mega tr does ride a lot better than the Five, the RP23 on the Five never feeling right, despite being tuned and fiddled with. With the Mega TR I set the air pressure on the Monarch RC3 so I had 30% sag, got the rebound set and havent touched it. Rear of the bike feels much more composed and doesnt blow through its travel like the Five did.
I too have a dh bike (Morewood Makulu) and felt the Mega AM was a bit much for general riding around. Wanted to keep the weight down so it could be ridden all day. Only thing I would potentially change, is replace the revelations with a set of Pikes.