I have and use the MLCS extender. It extends the bit a little too far for my liking, but until I picked up a Jacobs Power Collet, it was one of the 1 or 2 solutions for a plunge router out there (the Jacobs Power Collet was on closeout). The Power Collet appears to extend the bit a perfect distance for my DW625, but I don't have any long term experience. I say long term because the collet is a quick change concept where you put the bit into the collet and push the outer ring down and it "snaps" on the bit tightly. It is great for above the table bit changes in seconds.
I did a search on the web and never found any real problem with the design, but since it went out of production about 3 years or so ago, I have not seen any recent posts either positive or negative. If anyone has some knowledge about its long term performance, please let me know. I can understand why it went out of favor for handheld use. It demanded extenders for the baseplate of the router and I am sure that was not acceptable to the majority of router owners.