My thoughts on shooting lead in 44 Mag(and other magnums) in general, without any experience with these particular bullets:
1. Most leading comes from bullets that are too hard. Hard bullets don't obturate properly to the bore, and you can end up with combustion gases leaking around the base and effectively soldering lead to the barrel. This type of leading is very difficult to remove, while "streaking" from running a soft bullet at high velocity usually brushes out easily.
As an example to this point-22LRs are dead soft pure swaged lead, and usually run at 1000-1200fps depending on barrel weight. When was the last time you had a badly leaded 22?
I shoot a lot of Missouri "Cowboy" bullets, which are around BHN 12. I've run these in various calibers at 700-1200fps and they don't lead.
2. Somewhat contrary to the above point, most modern S&Ws have an "EDM" barrel, which is almost glass smooth. My 629 "Mountain Gun" has this type of barrel. These are so smooth that there can be issues with bullet lube wetting the barrel properly, and they can lead like crazy even with everything done right. These barrels can usually be recognized because, aside from looking basically perfect, the rifling doesn't have the sharp edges typically seen in conventionally rifled guns.
3. If all else fails, tumble lubing in Lee Liquid Alox will usually keep most anything from leading and is easy to do.