I've been working on my 100% run on death incarnate, which I feel should be the standard.
I think people should be allowed to run either 1.00 or the 1.42d patch as long as it's specified.
For reference, I know Half-Life has different categories based on how you run the game. You can use the BunnymodXT injector to re-enable bunnyhopping in the standard Steam version which allows way more people to get into the game, or you can download mods of the game that will make it behave as older versions of the game (the pre-Steam "WON" version), and then there's also the NGHL Half-Life client which is also a mod. And Half-Life is very popular for speedrunning.
You can speedrun the Steam version if you download the 1.42d unofficial patch that is listed in the resources section. 100% legal.