Agree totally that you should always wear a lid.
Was standing up to the stumps on a low, slow wicket, no lid. Never even considered getting hit in the face whilst keeping before, assumed my hands would do their job and catch the ball. Considered a helmet necessary to prevent damage from someone's bat cracking my head, as i trusted my reflexes (and the opposition) i didn't think this was going to happen.
Opposition were on the ropes but a real limpet of a number 9 was batting well, leaving everything possible to try and see out the remaining overs to prevent us from having 60 odd overs to chase down 90. He was really getting his front pad out there, really planting it a long way down and getting his hands in the air. One ball turned a fair bit further than previous deliveries and flicked up off the top of his pad right into my face.
Fractured my front tooth just above the gumline. I bent it back into place and finished the game, then went to hospital, where they fixed it into place temporarily and suggested i went to the dentist asap.
Nearly 6 months, and 3 dentist trips later, i had a £400 bill for root canal work which will keep my tooth intact for a maximum of 10 years. After it disintegrates i'll need a titanium implant replacement tooth, and i'll be lucky to get change out of a grand.
Helmet costs what, roughly £100? Don't take the risk.