You said you had a very low ceiling, in my (very limited) experience of working with LEDs, I found that beam spread left a lot to be desired. Also, the LEDrain is advertised as "2-channel DMX-512 LEDnarrow beam so you would get very little beam spread to wash a stage. It says it has a beam of 14.5, so you would have a very hard time getting a wash with this. Much more an effectfixture then a fixture to light the stage with.
What dimming system do you have, and do you have power in your room to add more dimmers if needed. If you do, I would suggest using LEDs as purely effects, and instead looking at conventional fixtures to get to a point where you can light people decently on stage. You said you have a low ceiling. If you take two 50' or 90' Source4's and place them at the rear corners, you could get decent back light, and probably increase the stage look. Side light, same thing, take some 50' or 90' Source4s as far off stage as you can go (or the corners of the stage) and get some side light into that. Once people on stage can be seen nicely, then I would start looking at effects.
What is your monetary budget, for that matter?
In terms of the fixtures that you have chosen, I have very little knowledge of them. The LEDrain, as I said, has a relatively narrow beam angle, so keep that in mind. It looks to me a lot like a dj light, and especially since Chauvet is more of a DJ company then a theatrical company. While a light in a tin can works, the brightness of the LEDrain may not be up to what you would want (especially since it is listed as 41.8 foot-candles at 3 feet)
I do not know much about the Trackpod either, but I would again point out to the 15' beam spread, probably would have a hard time of washing your stage. I also see the list price as $1499.95, which again would make me suggest a few source4s, to light the people, and then a separate fixture that could do effects (cheap moving head fixture perhaps).
Of course, this is just my opinion. What is your budget, and do you have any dimmers available or do you have the power in the space to add dimmers.
I would suggest looking at a source4 in addition to a dichrotic color mixer, such as the sea changer or High Ends Color Merge.
This will give you the color mixing changing capabilities you want, and you will be able to find a fixture to wash your stage.
This is a personal preference, as I really have not yet jumped on the LED bandwagon for stage lighting. I think they make great effects, low power draw, small, low heat, but I don't trust them to do the best job for lighting a full stage.
I think eventually led's will play a major role in productions. Problem today is that the low end units are simply not powerful enough to work with conventional lighting. There are some higher end elation units coming that use 1 wattled's that could be useful for washing etc.
On led's today, white is a problem unless you get a white ledunit, and again the current problem is lack of lumens. Color mixing varies, with some better performance in the lighter shades.
The advantage of led's is that they don't require dimmer packs but do need dmx channels, Some of the low end units use 6 channels per instrument. If you were going that way in the future you could add additional dmx devices and have them all be controlled via a PC based system, for say your intelligents and led's or what ever, and not have to upgrade at this time. Not familiar with that board, but sometimes you can also drive the board via dmx input from a pc based solution.
the size of the stage and distance are only part of the equation, how these will work alongside your other instruments which have much higher lumen output. What gels are you using on your pars? have you looked ad diffusion gels? Are you using them on dimmers? While the white led's will work for "spots" you then loose the color mixing ability.
With what you have listed so far, how are you using up all your 72 channels?
It is no problem having multiple instruments all with the same DMS address of course they will all respond to the same commands.
Anyway seems like you have made up your mind already, so report back on how it works