July will be almost as perfect, but there is a higher chance of afternoon thunderstorms on the high passes. On days where you are going up very high (Rocky Mountain National Park) it is worth getting started as early as you can, and trying to be off the top of the pass by mid day.
The June/July weather pattern in the mountains is beautiful calm cool early morning, warm mid morning, then as the temperatures down below increase, thunderclouds build rapidly over the mountain tops. It might take as little as an hour, to go from totally clear sky to big storm clouds. The clouds can produce heavy rain and hail, and lightning, and strong wind can come out from the cloud. The storms happen most often between 2-5 in the afternoon, and then stop, leaving the rest of the day beautiful again. It usually only lasts an hour or so.
Take lightning seriously, if you are caught out on top of a pass and there is lightning around you, seek shelter in a building or car and wait for the storm to pass.
In July, this happens almost every day, but if you are down on the side of the mountain instead of the top, it's not a big problem. I toured in CO in July a few years ago, riding almost all the high mountain passes, and I only got really rained on once - just try to get off the top early.
As to the Camping Gaz, I'm not an expert about this, but I kind of think we *don't* have that product in the US. You'll have to do your own homework. There is a big out door store in Salt Lake City (and lots of other places) REI (
www.rei.com) and camping stores in Jackson, so you might end up needing to buy a new stove here.