Hi - This is a good dervish build, stop asking if yours is.

Yes, it's very useful against the primary target.
The problem with the initial build is that it has rarely any attack skills. So [[asuran scan] will boost the auto-attack damage most of the time, which doesn't really do that much.
An attack skill will give +30 armor ignoring damage to all targets hit by the scythe, which clearly beats auto attack + [[asuran scan].
Let's look at 10 seconds here: That means one [[wearying strike], two [[mystic sweep] and 4 normal attacks. With my combo you get one [[wearying strike], two [[mystic sweep], two [[eremite's attack] and two [[victorious sweep]. Even against a single target the bonus damage from attack skills can nearly compete with [[asuran scan]. Here's some numbers for you.

14 scythe mastery
Kurzick Title Track rank 7
Asura Title Track rank 10

[Victorious Sweep] critical 60 ar foe [115] [86+29] damage
[Victorious sweep] ctitical 60 ar foe while enchanted with [Aura of holy might] [163] damage

Auto-attack critical 60 ar foe [86] damage
Auto-attack critical 60 ar foe hexed with [Asuran Scan] [150] damage
Auto-attack critical 60 ar foe hexed with [Asuran Scan] while enchanted with [Aura of Holy Might] [234] damage

That's 35 additional points of damage auto attack vs [victorious sweep] with [asuran scan] and a 71 point difference with [Asuran Scan]+[Aura of Holy Might].

I dunno about you but 71 points of damage is pretty substantial. This is just auto-attacking. The skills in the Wounding strike build posted earlier recharge quickly allowing for a two attack spike with deep wound possible every 4 seconds. If you get lucky you could possibly hit a foe for 498 damage and applied a deep wound.