I'm relatively new to this forum, and to cooking BIR curries, but I made my first batch of Darth's base sauce a while back. Due to the constraints of the utensils I had at the time I had to downsize Darth's recipe by 50%. I have to say that the resulting base was excellent, and although I haven't made a full-size batch I can't imagine doubling my ingredients would have made much difference to the final result, particularly since it is, after all, a base and lots of different spices and ingredients are added when the base is used to make a curry.
I'm going to make another batch later today (used-up the original batch :-) and this time it will be the full size, so I might be in a better position to comment.
One thing that strikes me is that it is really important to use large amounts of oil in the base, I was tempted to lower the quantity Darth says to use, because it seems excessive, but I didn't and I'm glad I didn't. I might add a bit more this time, and drain-off some of the excess to store and use in the final curry.