I've never understood the antagonism against tensiometers. It's a tool (Tim from Tooltalk: More Power!), like a torque wrench. After someone has built a certain number of bike wheels, or tightened a larger number of bolts, they may develop a feel for what's right and adequate. Using the appropriate tool lets a beginner, or an amateur mechanic, get the spokes even and balanced, or the bolt tightened correctly. Use the tool until you've been doing this kind of thing for 10,000 hours, 5 years of 40 hours per week.