TL;DR "Buffer" to "bio fuel" conversion rate is 1mB/tick (20mB/second).
(MineFactory Reloaded version 2.7.4-255, Direwolf20 pack 1.0.11)
I can't seem to find good information on the reactor, but wild claims by the dozen.
The one thing that is immediately evident is, that it generates more fuel per item the more types you supply. This information is on several wikis even.
The bottleneck seems to be the internal conversion of purple buffer to biofuel.
I found exactly this. I timed it and 1000mB (millibuckets = 1 Bucket) took 50 seconds.
Considering that 1 tick is 50 milliseconds and 20 ticks (best case) happen in 1 second, that makes 1000mB in 50,000ms (or 1000 ticks). No matter how many different types of items you supply, the buffer gauge will always only convert at 1mB per tick, or 20mB per second indeed.
Now also considering the cheapest BuildCraft fluid pipes transport 10mB per tick (i.e. 200mB per second), neither the pipes nor the fluiducts (thermal expansion) will ever be fully utilized by one bio reactor. As this seems to baffle some users here.
Now if you wait until the "bio fuel" gauge hits full (not the "buffer" gauge), you can very very quickly drain its internal tank.
I don't know if you can use this type of bio fuel in other engines, but MineFactory's biofuel generator does not chug a whole lot of it, while still easily powering more than a handful of machines.
[...]stick a bunch of ducts to pull out the whole 1440mb/t.
This is a slight and critical misconception. If you use 9 different types of items, you generate 1440mB
per operation, though still at a rate of 1mB/tick.
As such, 1440mB per operation at 1mB/tick * 50 milliseconds per tick = 72,000 milliseconds. This means, if you're using 9 different types of items, you will have to supply 1 of each every 72 seconds to keep the reactor running.
I've also found that 64 of one type of item only generates 320mB, that's 5mB per item (4 items/second) instead of 80mB as listed on wikis. To find the correct value, refer to the reactor's ingame UI ("Efficiency" bar). 9 types of items now actually generate only 1425mB per operation, close to the old figure, but it needs 71,250 milliseconds per batch of items consumed.
The rates for 1 through 9 types of items are 5, 25, 70, 150, 275, 455, 700, 1020, and 1425 millibuckets per batch of items. Remember though, still at a rate of 1mB/tick!