UK's Spectris falls after terminating Advent's buyout offer in favour of KKR
** British scientific instruments maker Spectris SXS.L down 3.6% at 4015p ** SXS said on Friday it had decided not to proceed with U.S. private equity firm Advent's buyout proposal ** SXS's decision comes days after backing rival suitor KKR's KKR.N $6.4 bln offer ** Stock up 66% YTD vs FTSE mid-caps' .FTMC 6.36% rise (Reporting by Ankita Bora in Bengaluru) ((Ankita.Bora@thomsonreuters.com))