I got one of the refurb Fuze + units and now understand the frustration expressed over the touch panel. Since I do embedded processor control as part of my day job I've been speculating why these touch controls are so slow to respond.
Speculation on my part, warning!
I think the answer is in the fairly powerful imx233 processor used in these units. The problem is that it eats a fair amount of power while it is running. So, to give long battery life the unit goes to sleep, and plays back using the DMA (direct memory access) capability that runs at much lower power. The processor wakes up periodically to keep the data flowing from external memory, and I suspect it only checks the touch pad then, creating an annoying case of variable latency. This is why it sometimes responds fast and other times slow.
But honest Sandisk, most users would gladly take half the operating time for a more responsive touch pad!
The Fuze + unit is the only Sansa player that uses the I.MX.233 processor