I have played with reduced loads quite a bit. Most in 270's and 22-250's for kids. Just recently started playing with some subsonic loads in a 338-06.
I know you stated 2000 fps or so, but do not discount starting loads from the manuals. A 200gr bullet and starting powder charge can be very pleasant to shoot.
I have used H4895 reduced loads and Trail boss, both work. Softer bullets (sierra, SST, etc) will work great with starting loads, and if you want to go lower in velocity, the FTX is a good choice.
I am going to get some 338 FTX's to try in my 338-06 subsonic loads next. I just used some bullets I had on hand for initial testing.
