http://www.xcmag.com/2015/11/which-flight-instrument-is-right-for-you-full-article-from-xc160/

The soaring pilot If you’re starting out, your priority should be
learning your core flying skills. Instruments should be simple and easy to use.

Naviter’s Andrej Kolar says, “Any instrumentation you use shouldn’t distract you
from flying the wing. Getting used to the wing and how it reacts in turbulent
air is the priority.”

An audio-only vario is perfect – it allows you to get a feel for what the air is
doing without having to be constantly looking at a screen. Unless you are flying
a hill that sits under airspace, you shouldn’t need to worry about your
altitude, and you’ll start building a feel for how far you can glide.

Many pilots – including Bruce Goldsmith – suggest you learn to thermal without
any instruments at all. “Ditching the vario enables you to concentrate on
searching for better lift rather than getting your senses flooded by what lift
you just flew through,” he explains.