I really wanted wireless because (a) I detect in a lof of thickets and brush and (b) it is a pain digging (espeically on a slope) without the cord getting in the way constantly. I finally settled on the Sennheiser RS160 set (HDR 160 headphones + portable transmitter). The transmitter is a bit big, but it fits fine on the back of my 705 control box with a bit of velcro (or a couple of rubber bands in a pinch.) Doesn't add much weight, batteries last for hours and hours (I use rechargeable obviously), and most importantly there is no delay in the signal like I encountered with many bluetooth wireless headphones.
If you're interested, shop around. I picked up a refurbished pair for about 70% off retail, with a 1 yr warranty. (Check Amazon's "used" listings for scratch & dent and refurbs too.) Also, while the headphones that come with the RS160 are fine, I ended up also buying the headphones that come with the next model up. (HDR 180 - headphones only.) The 160s are completely closed, while the 180s are "open" so some sound can pass through. Makes it easier to hear your pinpointer