Thanks to people here, craigslist, BrewDemon, and eBay I've got several boxes (cases) of the Mr. Beer & BrewDemon 1 Liter plastic bottles. However, thanks to my supervisor and co-workers I've also got several cases of the 12oz glass bottles (mostly Samuel Adams).
When I've been bottling my 1G recipes I use 12oz bottles. When I bottle my 5G recipes I use 12-24 12oz bottles (makes for easy sharing and if they don't come back, no big loss) and the rest in the 1L plastic bottles (these take up less room storing while carbonating/conditioning and later in the refrigerator, plus each one is more or less equivalent to 3 12oz bottles).
I've had very few problems with the 1L bottles, mainly a few that never pressurized due to non-sealing leaking caps. Which I found and got rid of those type of caps.
Or maybe I just need to brew a lot more and use all the bottles I have available?

Just thinking out loud, Thanks,