I wouldn't say the .44mag is out of steam at 200yrds - the 300grn load I run is trucking harder at 200yrds than a standard .45colt or 357mag at the muzzle!
300grn XTP still just over 1,000fps at 200yrds. It's 13MOA of correction compared to my 100yrd zero, so that's a bit much to deal with, and of course, I have to stay well practiced to keep it under 4MOA at 200yrds, but a 6-8" group will kill deer. Granted, that's firing a scoped revolver from a tripod and pistol rest, which is a little different than shooting a scoped rifle, but the power is there - it's just a matter of keeping it on target.
I'd also point out, the Leverevolution FTX actually has a poor BC compared to its field. The 200grn XTP has a shorter bearing surface, meaning a guy can push it harder without creating pressure issues, and it's a shorter bullet, meaning I can seat it out farther, also creating less pressure, let alone feed it from a longer case <-- less pressure still, AND lighter weight, so greater speed... Oh, and it also has a slightly better BC than the 225 FTX, so the stubby 200 XTP keeps that speed just as well as the pointy FTX. As does the 240 and 300grn XTP. The 180 XTP is the only bullet Hornady makes with a worse BC than the 225 FTX. The FTX is a great bullet, very good expansion, reliable, accurate, and relatively cheap, but it's not actually an improvement in ballistics.
Not many folks should be taking 200yrd shots with 44mags, even in a levergun, but it's really just about trajectory management and precision (or lack thereof), as the bullet will have plenty of punch to kill.