I am looking for a dark sounding string that I can play both Pizz and Arco. I would like to know what the term "Gut Core" refers to. Is this a gut string with metal outer windings? If so what are some good choices? From what I have read, it seems that E A and occassionally D are metal and the G is plain gut. Is this correct? I do not want to use plain gut as it is a bear to bow and too high maintainence. I would go with Obligato's, but I hear they have a short life, have winding problems, and roll under the bow. Superfexibles would be good, but the guages are weird. Dominants seem to have a breakage issue, Belcatos bow well but aren't that good for pizz. Any other suggestions, or should I stick with the Spiro Weichs? Not real dark sounding, but workable.