A while ago, I ordered about £40 of strings from Thomann- same gauges, but different brands, and different price brackets. One of the more pricey packs, were a set of SIT Power Wound 9-46s. Having snapped a string on my Charvel, I decided to put these SIT strings on to see what they were like. Within a few minutes of stringing up, the strings stopped stretching, and even with trem usage, they held tuning very well. After playing for about 20mins, i left the guitar alone, and this morning it's still in perfect tuning. This is the least hassle i've ever had with strings and a trem, and i'll certainly be ordering more- I don't change strings that often, so I can't really offer a tonal comparison, but they don't sound bad at all- harmonics jump off, and are wonderfully clear.
If you have a trem on your guitar, i'd really recommend using these strings, they save such a headache :) No wonder they're called Stay In Tune strings, they actually work!