Front what I can tell, the new JM-4 doesn’t do reverse or half speed and I doubt it can sync to midi clock. But hay how about those snazzy generic backing tracks????????????....Whatever……..
But on the other hand , lurking inside the new Line 6 M-13 , which is essentially every modeler they have created in one unit, is a new and improved DL-4, that boasts 28 seconds of loop time at normal track speed (double that length for half speed), separate switches for half speed and reverse, and an undo function, and another feature with perhaps the most creative potential, a switch that allows you to toggle the looper between post and pre placement…Way Cool. I tried this with a filter model and a little delay to create a polyrhythm and it was really nice to be able to switch back and forth between having the loop processed and not. Still no midi sync as far as I can tell, though the tap tempo feature can sync up both delay and modulation effects. You have to hold a dedicated switch to enter loop mode but the switches for the looper are wisely placed on the two rows closest to the performer. The down side if there is one is having to pony up for all the extra modelers, but I think it retails for around $500 so for what it has to offer, an array of distortion, fuzz and overdrives, all of there great delays, modulation and filter models, reverbs, and upgraded looper, all running simultaneously, with more programmability, two expression pedal ports, etc., its pretty intriguing. It has newly designed switches, though whether they are more or less robust remains to be seen. They have a slightly less audible click from what I could tell.
I have always been a fan of the DL-4, I understand a number of you have had issues with the switches, and it has been my experience that the main culprit in there failure for me has been when I have allowed the nuts attaching the switches to get loose. If they get loose enough it allows the switch to lean slightly and can cause the plunger to miss align on the contact switch, which, if done with enough force can even cause the little plastic cylinder in the spring, or even the spring itself to come off. So I make sure to, hmhhm, keep my nuts tight….If there is a bright side to this some what cheap design, the switches themselves are available from the company, unlike from some companies (behringer, are you listening?...no I didn’t think so) , and though replacement requires removing the main board to get to, are easy to replace and fairly cheap.