I got a SC52w-L2 from IS this week. I posted a review of the differences between it and the older SC52, but as for the button, here is my summary:
The SC52w-L2 switch is definitely softer than the SC52. It takes approximately half the pressure to activate the button compared to the SC52 (which I think is definitely hard). However, the SC52w-L2 takes about 4x the pressure to activate compared to a TV remote control (which is definitely mushy). So, I would say it's "soft", but I wouldn't go as far as "mushy". It makes a clicking sound, but it's more quiet than the SC52.
Another difference is the amount that the button is raised. My SC52w-L2 button is slightly more recessed than my SC52, approximately 0.5mm. This makes it more difficult to "double-click" if you have a fat thumb. I have to make sure my thumb is well centered over the button if I'm double-clicking to change modes. Or maybe it's because there's less tactile feedback than the hard SC52 button (which I'm used to).
Whatever the cause, I don't have any problems with single presses. But I sometimes fail to properly double-click. Maybe this will just take some adjusting to the softer button before I get it right. Right now, I still prefer the hard-click of the SC52.
Another issue that came up in a different thread is how well centered the electronic switch button is under the rubber cap. I think the button on my SC52w-L2 may be positioned slightly above dead-center. It's more difficult to activate the button if I press below center than if I press above center. So I think there's some tolerances in button placement, which is not surprising. Pressing in the center is no problem, though, and as I said earlier, you kind of need to because the depression has a small diameter and stops fat thumbs.
Oh, and there are only two stobe modes. A blinkie, and a rapid stobe.