Reply to S4 Durability

Having played with an S4 on display I really feel it is well constructed.

I'm debating whether to get an S4 or Denon MC6000. Owning Denon's over the last 5 or so years they have been well built and I've never had hardware problems with them.

For all you S4 owners how are your units regarding durability/reliability? Have you had hardware issues with them?

I'm reading the FX buttons are giving problems sticking/not responding and some other issues with lights and fader's.

From a scale of 1 to 5, 1 being very bad and 5 being excellent, what would you rate the S4 regarding durability/reliability?