There's no simple answer, unfortunately.
Before any upgrades go in, the nodes search algorithm moves one pipe section per second (roughly). It seems to buffer MJ as fast as it is sent, up to 6400mj.
Once the algo reaches a thing to give power to, it dumps half it's current MJ buffer into that thing then moves on. In this way, you can get it to power a sequence of machines. Bear in mind that it will be absorbing more power as the algo moves down the pipe, so it won't be quite 50% to the first, 1/4 to the second, 1/8 to the third: however, it /will/ take a while to reach the last machine in the chain. When it reaches the end, it'll start over. I avoid loops, they don't seem to help at all.
I think at absolute best, it will transmit 3200MJ per tick to an adjacent machine. It should, mathematically, distribute it's input power evenly over the chain, but you'll see noticable 'spikes' in any machine that has a longer 'gap' before it.
Say N is the node, - is a pipe section, + is a pipe section connection to something, M is a Machine and F is a powered Furnace of some sort:
N---+---+-+-+
......M...F..F..F
(the .'s are just spacers)
M and the first F will both be receiving more power than the other two F's. The last two will probably get about the same amount. The more speed upgrades you've used, the more even the power distribution will be.
I tend not to use them: Redstone Conduits seem to be roughly as lag friendly, and far easier to manage (particularly in terms of throttling output via Redstone Energy Cells). Transfer pipes are awesome for moving items or liquids, but the power supply problem is quite different to barrels and chests.
