I've got an SR Mariner speedo (DKT-5), had it since ~1980. I like it - reads to .01 knot (once you're going fast enough to turn the wheel!). I've had to replace the sender unit once. Original sender unit just wasn't doing it's thing - could no longer adjust into calibration. New sender is currently working fine. No complaints with SR Mariner - sorry to hear they seem to be going 'belly up'.
Wind instruments are in a tough location - lots of movement up there! Coming W through the Cape Cod canal in a friends' boat, we hit the chop at the W end of the canal and tore the B&G wind instrument right off the top of the mast. 60' carbon fiber stick in a 39' Lathrop custom. Had to stop in Hadley's to sort things out.