I use these strings on a BC Rich Warlock, and I play extreme metal. Mostly in the realms of grindcore and doom metal. As far as tunings go, I tend to stay in E standard and drop D - although I do sometimes downtune more depending on what I'm playing.
These strings are fantastic for what I play - the heavy bottoms really add weight to the bottom end, making low notes ring out with the desired heavy sound. Palm muting is a breeze as well. Tremolo picking can be a bit difficult at times on the E string, but this can be countered by just making sure your hand is placed right. The higher strings are nice and smooth, and they react nicely to playing fast. They can cope with some pretty severe bending as well, which is always nice.
Although I mostly stay in E standard tuning, these strings can go lower pretty well. Taking them down to D standard is still very much playable. Drop C or C# is possible, but that is getting into the realms of strings being a bit floppy and loose. I have taken them down to B standard before, and it wasn't completely unusable - certainly, to record a demo or idea, it would be alright.
They also hold their tuning very well - and I've never had any slip on me, and every time I've broken a string, it's been because it was a few months old.
My only gripe with these strings is that they don't last all that long - the thicker strings have a decent life, but the plain strings can feel very rusty and gritty after not too long - and that is with me wiping down the strings after every time playing it.
Overall though, these strings are pretty great. Well worth the small amount of money they cost. They don't last the longest, but buying in bulk will sort out that particular problem. Definitely recommended.