I normally don't use a scythe on my Ranger, Ritualist, nor Warrior so keep in mind that the following had a scythe that was NOT customized for those 3 professions.
I have rank 12 Kurzick/Luxon so my Aura of Holy Might was maxed.
Last thing: keep in mind that the Master of Damage has 60 armor. The Warrior and Ritualist would obviously have a higher DPS, compared to the other professions, against foes with a higher armor rating.
Rt/D -> 97 DPS with a 281 spike (14 Spawning, 10 Channeling)
Yes, my build was kinda random since energy management was a problem. I had maxed Sunspear (for Vampirism) and maxed Asuran but, if my scythe was customized, I might have bumped my DPS to 110 or so.
R/D -> 96 DPS with a 257 spike (15 Expertise, 7 Beastmastery)
I used Never Rampage Alone for a 25% IAS. My Ranger had rank 5 Asuran so Asuran Scan did only +59% instead of +75% damage. If my scythe was customized and if I had maxed Asuran, I might have bumped my DPS to 130 or so.
W/D -> 106 DPS with a 306 spike (16 Strength)
My Asuran rank was only 4 so Asuran Scan did +57% instead of +75% damage. If I had maxed Asuran and a customized scythe might have improved my DPS to 145 or so.
D -> 145 DPS with a 554 spike (15 Scythe Mastery)
I did use alcohol. My Asuran and Delver ranks were both 5 so Asuran Scan did only +59% instead of +75% damage and Drunken Master gave me a +29% IAS instead of +33%. And, this time, I had a customized scythe
. If I had maxed ranks, I might have bumped my DPS to 170 or so.
A/D -> 212 DPS with a 579 spike (16 Critical Strikes)
Uploaded with ImageShack.us
I had maxed Sunspear and Asuran ranks, and a customized scythe. I don't think there was any way to increase my DPS further.
Sorry I couldn't give you a perfect comparison but that's the best I could do.
I think it's pretty clear that Assassins are by far the best scythe users and I was surprised how the Ritualist, Ranger and Warrior did less damage than the Dervish.