By "significant amount of time", I mean through nightfall, factions, and eotn. Various hm dungeons and vq's as well. I'm mainly going to be writing without editing my words, since I want to get everything down. so of course, it will be biased.
I tried to make a derv who performed in the typical derv fashion. That is, a scythe user who used various enchants offensively and defensively.
In that respect, I tried to use a 12+1+1 scythe, 8+1 mysticism, 10+1 wind or earth prayers unless it was a heavy mysticism build or something. I also changed my elite at various points to see how the underused skills worked in play. Here's a short list:
1. Conditions are pretty fun to spam. Cripple especially. There are a bajillion ways to spread cripple with a derv, but honestly, pretty much all of them have relatively unspectacular effects otherwise. I suppose that's a fair balance for the condition, as it fit in with RoJ smiter I sometimes used.
Obviously, this thread is going to be visited by the "Who cares about anything else if the enemy is dead" people. Yeah, I usually run those types of team setups. But when I play my derv and can easily apply a cripple (cheaply too), snaring for more powerful AOE actually becomes kind of fun.
2. Onslaught is a mediocre elite. However! I really like the 1/4 activation time. Seriously, compared to Heart of Fury's 3/4 activation time, Onslaught was a godsend. Extrapolating that idea, I think an easy fix to the conundrum of derv enchantment dps (besides the hm/AL-dependent damage thing eles also suffer from) would be to reduce activation times to 1/4. Course, that's a poorly thought out idea but I'm sure someone could come in and tell me why it's a bad idea.
3. The 2 armor stances in wind and earth are great, but wind's Vow of Piety seems slightly underpowered compared to earth. I like Vow of Piety's stance renewal effect, but it's a lot less conducive to typical play than conviction's mechanics. One basically has to juggle enchantments as one is running from mob to mob. This is pretty similar to a MM, so I guess this type of mid-mob maintenance isn't terrible. I just wanted to say that if I had equal points in earth and wind, I would always choose conviction over vow of piety.
4. Bar compression is kind of poor. I suppose that's due to the fact that most of my bars have some key skills (+24 AL stance, faithful intervention, Aura of Holy Might), some pve skills (AoHM, 2 others), an elite, and then you have to fit ias and scythe attacks in...it's a pretty big mess. I think I feel obligated to take the defensive skills because they are just so good (aka the stance and faithful intervention).
If you're running an avatar, it's going to cost you 2 skill slots (even ignoring the fact that if you have to cast mid battle, that's going to take ~4 secs to cast the avatar and then eternal aura). If there was a faster activation time, I might be more open to using avatars.
5. Finally, compared to my sin, ranger, and war who can all also run scythe builds...ALL of them do it better. Even with 12+1+3 scythe, the fact that all 3 have maintainable ias and that their primary attributes can be offensive based, it's really no contest.
Now, I don't like the idea of nerfing scythes for other professions, but given that all 3 pretty much require 12 in their primary to be effective, maybe buff mysticism's skills to a more equal footing or work in wind and earth prayers to enhance scything.
edit: oh yeah. Of course many people have already expressed these views. Since I know that the devs read this (supposedly) and that I'm a proud dervish user, my opinion might actually make a difference when dervishes come up for their skill balancing.
F

Its funny, we are now 5 years into this game and we are STILL discussing and recieving major skill rebalances...shouldn't this shit have been ironed out...oh I dunno....3 years ago(4 for core-classes)?
Yes, it should have