IMO Blackhorn 209 is the best thing that's happened for in-line muzzleloaders in years. Its easy to clean up, leaves no crud ring and is great for developing new loads. I usually start at 90 grs. and work up. With pellets you're stuck with using a two or three pellet load. The sweet spot for all of my rifles is 110gr of BH 209, Federal's 209A primer, a 250 or 300 gr Hornady SST bullet and a Harvester Black crush rib sabot or Hornady's EZ load sabot. To assure consistent loads I measure by volume and then weight my loads. I don't swab between loads. I rarely shoot more that 15 rounds at a range session, but I know of a number of folks that shoot up to a 100 rds, with no real change in pressure on the ramrod to load. Check Blackhorn's website for suggested load combinations etc. I have the Lehigh bare primer conversions on all 3 Knighs and my new Redemption has the optional loose powder breech plug. Some older guns may need a new BH209 breech plug to avoid hang fires. The other great benefit is the ability to leave the gun loaded for several days on a trip because it doesn't absorb moisture.

I use 3 white hots out of my pro hunter (28" barrel) and get about 2200 fps with a 250 gr Barnes bullet.

I know for a fact that loose Triple 7 powder burns more completely than pellets and you will likely get better consistency by measuring & having loose powder. I use to shoot 120 gr of loose triple 7 out of my older Black Knight MZL pushing a 300 gr Barnes Bullet.
Very consistent and accurate.

I use the white hot pellets now because it's easier (so I am lazy) and I really don't see any variation in accuracy out to about 200 yds. At 100 yards I can shot 1" groups if I keep a clean barrel.