I've turned over and over my insulation equation for a 6000 gutted 2x4 frame, 3 story, 6 unit building, in jersey city, nj.  The top floor has no attic. Ceilings are finished to the roof deck.

I decided to go for icynene ldr50 foam: 3.5" studs, 8" between rafters roof, 5" in attic floor.   I almost gave my deposit to the installer, but then started reading nightmarish stories about offgassing, the toxicity of fire retardants, the chemical waste involved in the process and why don't we use cotton, wool or demin etc...  

Here's a couple links:
http://blogs.howstuffworks.com/2009/05/14/how-icynene-foam-insulation-works/
http://www.greenbuildingadvisor.com/community/forum/green-products-and-materials/14537/out-gassing-bad-stuff-spray-foam-insulation

The challenge with batt methods is my studs run from 13" to 18", many are not straight, some are cut by diagonals.  Cutting batts of any kind isn't going to end up with a tight envelope.  Wet sprayed cellulose is tough to find although I havn't looked too hard yet...

I would appreciate any feedback about icynene or advice about alternatives.    

Thank you!!

I am not an Icynene dealer/installer, however, I have used the product several times over the last 10 or so years.
I have seen no problems with outgassing of the product. I fact, I have a piece of the cured foam here in my office that I show to clients who might be interested. Any outgassing that might occur happens within hours of the installation process. I have spent a lot of time working in homes after they were foamed, and have had no concerns. Go with the Icynene.

I've never seen toxic outgassing issues with half-pound Icynene (never used their 2lbs product).

If you 're still gun-shy on Icynene, dense-packed (3lb+) cellulose, will typically outperform it on R value, as will 1.8lb JM Spider blown fiberglass or higher-density installaions of Certainteed Optima. If it's bare studs you many need to use blown-in-bag/blanket methods to get the higher density, but in a lath & plaster or 1/2" wallboard situation it's usually possible to get there too. Wet-sprayed cellulose is lower density and performs comparably to half-pound Icynene as long as attention is paid to air-sealing. With higher density goods the impedance to air-flow is pretty good, and typically "tight enough", from an energy use point of view that air-sealing would be primarily for controlling moisture transport. In the mid-Atlantic states, with the hygric buffering of cellulose the air-transport issue is also somewhat moot if dense-packed. Wet sprayed in an open-stud situation is significantly cheaper than dense-packing however. From a cost/benefit POV it's not always possible to rationalize densepacking vs. tighter air-sealing + wet-spray.

Batts are impossible to get perfect even when the framing is consistent. In your situation it's hopeless. Wet sprayed cellulose or wet-sprayed (1.0lb) Spider are probably your best options for going cheap on it. Air sealing every stud bay and framing seam with caulk/foam before insulating can optimize performance, mitigate risk of moisture issues.