I recently purchased the M13 to add to my gears. i very impressed by the facility to create a FX set-up and the quality of FX sounds it make.
I look also for the HD500x, i like the fact that you can go up to 8 FX at the same time.
But since i using my Rocktron and / or Amp channel to created my overdrive or distorsion sounds, the need of amp simulaition wasn't nessecary.
What really make me decide to go with the M13 was the quantity of scene selectable, 12x, this wihtout have to hit button here and there to change bank.
I had several FX system in the past, Digitech, Boss, Rocktron (i like the sound), and many individual FX pedals, this M13 is by far the best i like,
Because it is so easy and flexible to adjust, copy, deplace as you want FX.
What can be improve on the M13:
I wish that Line 6 improve the U-Vibe, it a bit weak to get really the best Vibe on the market.
(i have to add a phaser in front to get a good effect, i losing one FX spot)
I wish that Line 6 improve the Rotatry Drum speed, by having more than just "Slow and Fast" as choice.
Can soemone from Line 6 can tell us if they are looking to provide any M13 update and what?