Yes, IMHO the MullerWorks 4 groove MI barrels are some of the best in the RFBR industry. Unfortunately, the supply has dried up and none have been available to the average competitor for some time now. I shoot two rifles, that have MW .900" 4 groove barrels fitted to 10X actions and both are excellent shooters, limited only by my shooting skills and the ammo available. Problems is, Killough SS has removed the MW 4 groove barrels from their website and now only offer the MW 8 groove barrels ... which must be special ordered. There is no proven track record for the MW 8 groove barrels ... that I am aware of.
My second choice in barrels would be the "Shilen Ratchet" which are more commonly available and perform extremely well in the major matches, as seen on the equipment lists. I have a Ratchet installed on a IR50 Sporter and also a 10.5 lb rifle. Both are competitive in local matches. Good luck on acquiring a new MullerWorks barrel anytime soon. John