I'm using a Quadra and Hassey H4D/40 for weddings Steven. I've never used a Ranger, so cannot comment.
Quadra Pros:
The Quadra is simply the smallest, lightest, least complex, most versatile solution going as far as my research could determine. If working alone without an assistant it's much easier to transport than most solutions (I use
http://www.thelightcaddy.com to transport the light stands, 60" umbrellas, cords etc. with the tiny Quadra heads already mounted on the stands and ready to go ... and a small Kata shoulder bag that perfectly fits the Quadra box and spare battery.
My most frequent use of the Quadra is: 1) lighting large wedding formals in lower light of a church using both heads
AND a Metz shoe mount ... 2) outdoor groups, families, and wedding formals using one head for directional light and more power, with a Metz shoe-mount or Potato masher for fill ... 3) Single Quadra head on a light pole and an 30" umbrella or 20" Beauty dish for directional light with the Metz shoe-mount or potato masher for fill.
IMO the Limitations are:
400w/s which are asymmetrically distributed when using 2 heads. Provides classic key and fill distribution. Whether 400w/s is a limitation is strictly determined by your shooting conditions, distance to subject, degree of light modification, and creative intentions ... i.e., if shooting with very bright backgrounds and desire to both stop down and use the fastest shutter speeds that the Skyport radio system will allow with a leaf shutter (see Guy's thread in the MF section about sync speeds and the Elinchrom Speed transmitter) ... then you may run out of w/s. Only you can determine that. Also using a shoe mount or potato masher Metz for general camera position additive fill helps boost this by about 70 to 100w/s
Limited use of light modifiers. While I do have the adapter which allows use of main-line Elinchrom light modifiers (other than large umbrellas, the Quadra modifiers are too small for lighting big groups of people), I would not recommend use of direct-mount large soft-boxes, especially outdoors (as Jack already knows, I am not a fan of the standard Elinchrom mount anyway, and the adapter isn't quite as robust as direct mounting to an Elinchrom head like with the Ranger). I got the Quadra to Elinchrom standard mount adapter for only one reason ... to use a 20" Elinchrom beauty dish mounted on a light pole wielded by an assistant. IMO, larger light modifiers could be used if they are the type that you mount the head separately without the head holding the weight of the modifier.
Be aware that the standard umbrella mount on the Quadra head only takes the slimmer Elinchrom spec shafts ... which I believe is true for all Elinchrom heads. I use a separate elbow type umbrella holder so I can use other larger 60" ribless umbrellas.
You will need the 11' and 16' extension cords for the heads. The Quadra comes with 8' head cords and they are too short.
I should add the cavate that I have a full blown Hensel Porty 1200 with heads etc. and a huge array of light modifiers for more demanding assignments where I have assistants. Eventually, I will secure one of the much smaller new Hensel Porty Lihtium battery kits. I also have a Braun 900 inverter to use any mono-head.
Here is the set-up I use with the H4D/40 to use the Metz shoe mount flash in tandem with the Quadra. It's a very light weight but very sturdy Kirk grip with Arca type quick release top and bottom, and I mount the Skyport on the handle ... sinc cord from Skyport to the Hassey sinc port. The Quadra comes with the correct sync cord.
The photo shows use of a Quadra head on location at a reception hall, positioned camera right using an 30" umbrella feathered off the background flowers, and the Metz for camera position fill. In this case I wanted to avoid showing the cluttered background with people milling around etc., so I used ISO 200, 1/180th shutter @ f/7 with the Quadra single head at about 320w/s and the Metz full manual. The low available light was not part of this shot at all.
-Marc