The way that I've always seen the LED vs halogen debate is the LED units are just another tool I can use in my designs. They are not a direct replacement for my halogen and discharge fixtures.
In terms of the cheap disco style lights, I am not impressed by the LED effects on the market in terms of brightness, coverage, and overall effectiveness. When I set up a system to light a high school homecoming or similar I still use a system based primarily of classic halogen effects such as the Vertigo and Aggressor, plus a pair of strobes, 4-6 discharge moving heads and my discharge centerpiece effect. No LEDs here, and the system works just fine, if not better than any LED system I have seen at this point. Not to bash the LED effects - I just don't have a use for any. I'd much rather see ADJ produce a line of high output discharge effects.
I'd consider swapping my moving heads for LED based units, but only when I can find something truly comparable to a name-brand 575w mover. I've seen the 5R based units and while impressive and a good alternate to a 250w or 300w discharge mover, I'd still choose a true 575 over the 5R. I think LEDs will eventually yield to the more efficient conventional lamps like the 5R and plasma based sources. When lighting people, I'll never swap my halogen Pars and Lekos for LED.
Now I understand that LED units are great for power tight situations, but realistically you'd want to have your lights on a separate circuit(s) from your sound system. That gives me at least 15A to use for lights, so I'd like to take advantage of that. Knowing that ADJ products are meant more for mobile DJs and clubs, it doesn't surprise me that they push LED fixtures because most of their customer base doesn't have access to 100kW of power on a nightly basis!
I have been considering an LED uplight/truss warmer solution for some time, but right now I don't think it's quite cost effective yet, but I can see making the investment in the next few years.