Squadron White works very well for me in just about every filling application. I've never dealt with the other stuff... "If it ain't broke, don't fix it."
Masking off small areas around the fill helps (Tamiya Tape works well because it's thin), plus I always thin my putty with Acetone (sold at beauty supply stores for finger nails). Nail polish remover (must have acetone) works well to thin too. The thinned putty dries very quickly, so you have to be fast. Putty thinned with Nail polish remover doesn't dry as fast as putty thinned with pure acetone, but it still dries pretty fast.
Shopping at Sally's Beauty Supply for modeling supplies seems wierd, but they have some great stuff for model builders. That's were I get sanding sticks, acetone, fine scissors and tweezers. I always pretend like it bothers me when my girlfriend wants to go into Sally's. "Oh alright, but just for 5 minutes."
Semper Fi,
Chris