Over a week of research for about 4 hours a day (!!!), I found a rather interesting, highly capable, relatively cost effective and very expandable studio lighting system. It's a hybrid between a pack/head and monolight system. The controls are in a pack on the ground and all of the heads have their own capacitors and plug into this pack so there's no loss in cables, even if they are 100' long or longer. Here's the pack:
Balcar CONCEPT P4
It's 4 x 1600W/s all digitally controlled over a 4 stop range, charges up to 1000W/s per second (three recharge speeds), gives independent control over each head, flash duration as fast as 1/1800s, has flash sequencer, lots of modelling light modes, and even has a connection for Apple Localtalk so you can network it in. I found some used at calumetphoto.com for $600US each. I only picked up one, I think there may be two left. Calumet looks like they are consolidating their systems because the concept line used heads different from Balcar's other heads.
The pack may be a great deal but what about the heads? Cheapest new heads are the CZ 2's from calumetphoto.com. They are about $600 off right now, so $300US each. 800W/s and you can't use them to focus the reflectors but with all of the other options available for light modifiers I was ready to settle for them. However, I discovered that the CONCEPT P4 also accepts the Balcar PSU and PSZ heads. I found an old non-Concept P4 pack packaged with four 1600W/s used heads with current reflectors (RX60's or something like that . . . faceted, 60degree) and offered $600 for it and got it at that price. I threw in an extra $50 for the Balcar umbrellas with diffusers. The set also came with some gigantic solid softbox . . . the Galaxy 4 x 4 or something. Shipping was going to be $200 for the softbox along and I wasn't going to use it so I just had the heads shipped.
Anyway, the old heads actually give you a larger range of output power because some of them can be stopped down as many as two stops because the original non-CONCEPT P4 powerpack didn't do asymmetric output adjustment. Only the CZ 4 ($1200US new) can stop down one and the CZ 2 can't be stopped down at the head at all. And they are compatible with all Balcar light modifiers. So $1200 plus shipping (about $100US total) and I have two powerpacks (the older as a spare), four heads, two umbrellas with diffusers, bunch of extra flash tubes. And the CONCEPT B3 pack is also compatible with the heads. the B3 is actually a battery-powered 4800W/s pack. Anyway, four heads and the older P4 power pack usually go for about $600US on eBay. And CONCEPT P4 power packs used at Calumet for $600US. I'm tempted to pick up another of these packs and finding some more heads . . . if I end up not needing them, a local photographer and good friend I mentioned this to has already offered to buy the setup for $2000CDN inclusive of shipping (about $1500-1600US).
The only drawback to this system is that the heads are about 7-9lbs instead of about 3-5lbs for most pack/head systems so you'll need bigger booms. But I think Balcar nailed this one . . . I was really happy to find that the old heads work on the new pack. The new pack makes the old heads just as good as the new heads for most purposes. And Balcar's one company which I believe has the widest selection of dedicated light modifiers that are also digital friendly (hot spot resistant, usually focusable).
Heheh, I hope this long rant helps someone. Have a great day. =)