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 Experimental evidence - reference would be good 

Perhaps a reference should be added to the value of 10 years. The paper given (K. Hagiwara et al., ""Particle Data Group current best estimates of proton lifetime"", Phys. Rev. D 66, 010001 (2002) ISBN 978-06848657680) dates from 2002 and is presumably from the 2001 Super-Kamiokande results. 

You will be aware that the average non-specialist reader will have seen 10 years, or just 10^33 years, and this is the value that other google sources bring up - from the same Super-Kamiokande experiment. e.g. the hyperphysics.phy-astr.gsu.edu site 

""As of [2001], it seems that the proton lifetime has been pushed out to [at least] 10^33 years."" (which point?)

Isn't 10^33 strictly equal to 10?   "