If you're going with packs, I'd recommend more than one pack so you don't have the problem of not having cables long enough to run to your strobes.
If you're doing outdoor shots, you really need to consider when you're shooting and what modifiers you're going to be shooting with. If you're shooting during the middle of the day and want to kill the sun, you're going to want a lot of power. A B800 is only 320w/s and won't cut it if you're shooting under bright sun, trying to bring down the ambient exposure, and shooting with a modifier that offers heavy diffusion. At that point I'd recomment a monolight that's putting out over 600w/s or possibly even more, if not even a pack and head system.
The benefit to a pack is that they generally supply a lot more power for a lot cheaper than a monolight. A 1000w/s pack will let you shoot with 1 light at 1000w/s; the problem starts where if you're adding more lights. 4 lights on a 1000w/s pack will get you 4 lights at 250w/s each and then you're going to be limited on how you can adjust the power going to each light. Unless you've spent something like $7000 on a Profoto D4 pack, you're not going to be able to individually adjust the power going to each light by 1/10 of a stop. That's one of the other reasons I would recommend multiple packs if you're shooting multiple lights.
Either way, there's a sacrific you're going to have to make. It took me a while to get what I did. I ended up with 5 Speedotron 202VF heads, a 1200w/s pack, and a 400w/s pack along with an Innovatronix Tronix Explorer XT battery. I bought everything but the battery used and it came out to about $2100. The only other thing I could use is another 1200w/s pack. I was originally looking at used Profoto gear, but that would have cost me $2,000-$2,500 for one 1200w/s pack with 2 heads used. And even with the purchase I made, that's not including lightstands, modifiers, a case to carry them in, etc... etc... etc...
But even after all that, I still have my speedlights because I believe that there is no one size fits all option out there, at least not for me. I have the speedlight setup when I need ultra portable lights and I have the pack and head system for when I need the power and the flexibility of better modifiers.
Check out Dynalite. They were another company that I was on the edge of going with, but with the price I got the used Speedotron gear for, I couldn't pass it up. And it's like buy a certain type of car; you never notice how many other people own that car until you own one. I've seen everything from shoots by Annie Leibowiz to Playboy shoots being down with Speedotron gear.