Very fortunately this thread happens to coincide with a whole bunch of testing that I am doing on various finishes, sealers, fillers etc.
So I have just now (between this post and the last) used the Intergrain filler on another length of the quilted Blackbutt....and not a black mark in sight! I would say that it is about 50% more expensive than Timbermate (at my local anyway), but I'm happy to pay that rather than have black crud in the grain. All other performance appears to be identical. The have slightly different colour ranges.
Here's a good tip when using either: rather than mix it with water, as shown in Ross's video link, I just spritzed a fine spray of water over the part I was working on. My thinking was that I want it to spread nicely, but I don't want to introduce too much water into the cracks (in this case) because it will take longer to dry and may give extra cause for a bit of shrinkage. The spritz just allowed a little more spreadability, just like Meadow Lea :D
At one point I sprayed a little too much so I was able to just scrape that up the other end and use it later. I found it best to spray from about 80-90cm above the board to get the right spread of water. :H