I've been using linecounters for years and never really relied on the readout being accurate.I use a shakespeare clamp-on counter and use that for my calibration of all the mismatched reels that I use.

I've used cabelas depth masters,depthmaster II, Abu garcia 5500LC,shakespeare tidewater,and 1 daiwa accudepth. Throw some backing on them and then a spool 120-150 yds of spiderwire. Some of the spools of the reels would be 1/4,half,and 3/4 full. I lose quite a few baits during season because of snags and my counters give me screwy numbers. Full lake,I'd get out 13 yds.2 months later,I'm getting out 15+ yds and the lake dropped 1'.

After years of mismatched reels with only 2 of them matched,I splurged on 4 clearance Diawa Accudepth 27w's. I couldn't pass up the $50 clearance price that cabelas had on them. Now I want consistancy in my setup.My setup calls for my cranks to occasionally bump the bottom of 6'-7' water with lots of stumps.I've got to know the exact measurement released to keep the bait in that killing zone just inches above bottom. Too close and snag city.Too high and trash fish city. So I got the reels in and spiderwire had $10 rebates on the 300 yd spools of 30# test.So I ordered 2 spools and split them in half to give each reel approx 150 yds. After trial and error,I have all 4 reels calibrated around 100' each.At 50' of actual tape measure,the counters read 52.

You see,if the spool isn't entirely full,you'll never get an accurate readout from the counter.There's a utube vid that explains how to calibrate linecounters.I was skeptical at first and didn't think much about accuracy,but that vid was dead on.1 thing I learned with matching reels,I spooled up the 1st 150 yds with spiderwire then uni-notted the mono backing on it and calibrated it that way.After hitting the 100' calibration point,then tie that reel to the next empty reel and load it up with backing 1st then the spiderwire.It's backwards,but works if you matching multiple reels. By the time you get to the last reel,you'll pretty much go by the numbers your previous reel read out.

Here's the vid:
http://www.youtube.com/watch?v=QNHHef2oIEo