The choice of a case is an entirely personal choice. Regardless of what case, if any, anyone uses, accidental damage voids the warranty, period. Pick the case that provides you with the security you are comfortable with.
But regardless, if you drop it or otherwise damage it, your warranty does not cover accidental damage, regardless of cause or circumstances. If this is a major concern for you, you may wish to consider buying AppleCare+ (which reduces the fees for accidental damage) or purchase independent handset insurance.
thin case is better than no case but would only really protect from scratches.
thicker case made of soft silicone raher than hard plastic is safer.
Would this case in particular protect my phone from 1-3 waist height drops? If not, what would be the outcomes?
If you want the best protection, Otter Box have the best protection for iPhones.
Defender is strongest, commuter is next in line a little lighter than Defender: http://www.otterbox.com
Should i wear a really thin case on my phone,
