[sciurius]

On my Samsung Note I have an anti-glare foil which greatly reduces reflections but also reduces brightness. It is really, really great for normal use but becomes a pain when used in heavy sunlight due to the reduced brightness.
My other tablet does not have anti-glare, so the brighness is higher, but it reflects like hell. Having a sun shield will hardly work since it is the reflections that kill readability.
When performing in bright sunlight I sometimes use the first, sometimes the other tablet, with varying success.

An e-ink tablet would be the best for this circumstances, I think.