I think it would be worth it if you actually had a way to ensure that the output was in fact the range of exposure you were wanting to achieve. However there are many variables to consider as you know. How heavily planted an enclosure is up to the screen top and what type of screen it is going through.
Right now without a solarmeter most are going on the typically recommended distances to a branch below the fixture. So for a 5.0 or 6% bulb in a single bulb T5HO fixture it needs a distance of 8-9 inches to the branch below it with a screen in between to get an approximate 3 UVI level where the chams body sits off the branch. Then for a 10.0 or 12% bulb in a single bulb T5HO fixture it needs a distance of 11-12 inches to the branch below it with a screen in between to get an approximate 3 UVI level where the chams body sits off the branch.
This still does not ensure the exact UVI as we know fixture type and reflector can make a big difference on output levels. Not to mention UVB reduction levels that happen naturally over the bulb "life". And again the screen type used that the fixture is going through.
What I will say is not many people are willing to spend money especially if they are new to the hobby. We recommend a solarmeter to be used to verify levels however many people do not buy one. When it comes to UVB most seem to just buy the cheapest they can get their hands on because of the expense of all the other items needed to provide correct husbandry.
I do think it being a 3 bulb unit and having daylight bulbs with it would make it more worth wild for people to buy. If you can make the price comparable to at least using 3 single T5HO fixtures. 2 with daylight bulbs and 1 with UVB. That alone would run someone about $150 cost of fixtures and UVB bulb.
Hi Beman.
Yes.
3 bulb seems to be what I am thinking about.
4 is allot and 2 just is not that much if someone has allot of plants.
The design in the works has 2 cords / 2 Independent switches.
So 2 bulbs can be on a timer
and then ONE bulb can be on a timer.
I am NOT going to do a built in timer...
why?
Because in my past experiences that can fudge up...... and then the whole fixtures is junk!
I feel that if TOO MUCH tech is incorporated into something that should be fairly simple, it creates just more planned obsolescence.
If someone wanted to then get 2 simple 6.99 timers they could:
Say....
Have ONE 6% bulb come on at 8 am for "sunrise"...
And then have the other set of TWO, the one Daylight and ONE more 6% come on at say around 10 or 11 AM for "mid day sun" when all 3 bulbs are on.
Two 6% and one daylight should create the approx. desired UV for the average 24 x 24 x 48 cage.
If someone wanted / needed more UV,
just swap out a 6% for a 12% ....or 14% on a super large cage or with a greater distances*
*ie. Like If lights were hanging 12" - 18" over banks of cages.... and going through screen.
Of course ---
I would test it out with screen anyway to make sure that a basking perch approx. 10" - 13" under the bulbs would get a UVI of about 2.8 - 3.2.
Also ...
there may be "magical panel" inserts available 

to create customizable "shaded" or lower UV levels IN CERTAIN AREAS.
Creating different Ferguson Zones ... if you subscibe to that line of thinking...
that can be added, removed or adjusted easily.
Ker-Pow Baby!
And maybe even a mini UV "Condensing" reflector to add/ focus in more UV to a basking area.
(probably better for like bearded dragons rather than Chams, but ya' never know.)
And it has to be packaged in such a way, with easy to understand instructions
so that that beginners and novices can use it with great success & TOTAL CONFIDENCE.
With Predicatable UV Results,
so that it can be successfully used even if the beginner or novice doesn't have access to a Solarmeter.
All for the low low price of ...... ????
DOH!
I DON'T KNOW YET 
BUT
It would be great if a 3 bulb t5 fixture like this was around a hundred bucks or less.
Cheers.
Todd
lightyourreptiles.com