Choosing betweenusing two or 5 machines

After running two and three characters in World of Warcraft the wrong way (ALT-tabbing really begins to hurt after a few months ) I ran across these forums and decided to start multilogging in a more sensible way. Taking Ellay's and Xzin's words to heart, I'm designing a better setup so I can do so more comfortably. While I understand the hardware requirements of the computers themselves, I'm kind of stuck on arranging input devices. Go get a beverage, this could take a while...

My current plan is to level up a group of five characters for whom faction gain is really important. This is going to mean a lot of instance grinding at higher levels, as I can gain faction for all five as a group faster than running them with PUGs on each character. Five different classes, three roles; I've done three characters, three roles already so I'm fairly used to it. My concern is how much control I need of each character. At least from 1-60 I can easily have one character (lvl 70) lead and the others on follow to kill, loot, repeat without much thought. This readily lends itself to running the followers on one system using Keyclone to group up and handle whatever casting is required. For 61-70 I'm a bit gunshy of continuing with this model. With the increased dangers of losing a follower (if the follow disconnect issues persist) and increased need of individual control for better CC and off-tanking, I'm looking at switching to each character to its own computer and monitor. Obviously, this is a bit of a jump in hardware but is at least manageable with gear from Vetra. So I'm faced with at least three options:

1) start with 4 characters on one system, main on the other then shift to one on each system. In the short term, it's cheaper and will get me comfortable with controlling 4 characters with one keyboard and one with the other which I'll probably need to do to avoid 8 port multipliers and wireless mice (lots of steel in my desk, shelving, and cases). It also will allow me to wait for the Penryn chip releases, with their fancy power usage reduction and cooler running than their Conroe counterparts. However, I'll need to adjust to a new monitor and KVM setup later; I'm not sure how wise that is to attempt.
2) 4 characters on one system, main on another all the time. Cheap? Check? Easy to set up? Check. Ready control and monitoring of individual characters? Not check. I'm really in need of input based on others' experiences with a heterogeneous group in level 70 instances for the much dreaded faction grind.
3) 5 separate systems from the start. Getting it done right at the start is a good idea, but I'm fighting both the looming new processor release which will provide a bit more future-proofing of the systems and the idea of not being in control of all the characters from one keyboard. Neither of the other options allow for this, but my experience with /follow has me leery of giving that up, expensive as that option is.

For now the first option is the forerunner in my mind. I'd appreciate any meaningful input or sharing of experience to help me move toward more effective multilogging.