I used 3Fg all the time in my 40/65.
It started when a friend sold me 8 pounds of Goex 3Fg real cheap. I liked it so well, when it was time to order a case I went with Goex 3Fg again. MV with a 430 gr bullet was 1250 fps. This is an outstanding load.
I have since switched to Swiss, also in 3Fg. Swiss is faster than Goex, and 66 gr Swiss 3Fg gives me 1310 fps with that same bullet.
I've heard that some shooters use 3F in their 45/70 with success.
That high MV (1300 fps) is needed for Creedmoor-type matches (800, 900, and 1000 yd). It is not necessary for shorter ranges (up to maybe 700 yd or so). It may even be that the lower MV (1150-1250 fps) is better for those shorter ranges.
As far as lube cookies go, I make my own but use them only for paper patch loads in a 45/100. I use my regular bullet lube, and pour it onto wax paper, about 1/10" thick. Then I just cut it out with the mouth of the cartridge case when loading.