(which was renamed simply the XL Pro about five years ago) their design goals were basically to retain the 6000 Di Pro SL's analog display, similar field performance, but lighten the unit up and configure it to 'fit' in the smaller 'Slim-Line' (SL) housing. If anything to improve performance, but not to sacrifice any.
The result was the 6000 Pro XL which only retained about 15-17 parts of the 6000 Di Pro SL.
They eliminated the Volume control and peaked it slightly higher by design. They enhanced the sensitivity a little, and in making things come together the new model was lighter, better balanced, more cost effective to operate, and could be used at a slightly slower sweep speed.
There are a few 5900 & 6000 Di Pro SL's out there that have a 4-tone audio ID modification, but they were done on the earlier 'XB' versions and not the final 'CB' versions. I was informed that he doesn't do them on the last issue ot the 6000 Di Pro SL and not any of the 6000 Pro XL/XL Pro.
As for electronic parts wearing out, you can't say 'NO' when we all know that TV's and computers and VCR's and all sorts of electronic devices get worn out in one way or the other. However, I have used several detectors that date from 1969 thru 1986 and they workl just as well today as they did then.
If a person get out and uses their detector enough in a year they will have paid for it either monitarily or just from the enjoyment factory such that they could part with it and start anew, compared with a lot of other hobby equipment. I wouldn't be too concerned, especially weith some of the more modern offerings.
Monte
