You asked about how a pyramid tent holds up to the elements. From the many I have seen over the years, they will take just about anything mother nature throws at them.
As for how they do with heavy rains - the only drawback I've heard is that the fly could stand to be larger to help keep water from coming in the door, also be sure the fly is sewn to the lodge - not one you tie on.
While on the subject of the door opening - one has to learn to pick up their feet due to the design. Again, this design helps keep the water out.
Agreed, being able to stand up in a one pole is limited - more so with the smaller ones. I wouldn't go with anything smaller than a 12 by 12.
You won't be able to walk around like you would with a wall tent - maybe with a 15 by 15 tall boy, you would be able to do so. Heating one this size will require an ozone to keep the heat from going straight to the top.
The time setting up a pyramid compared to a wall tent is about 1 to 6.
As for canvas and money - if your wanting it for hunting and your asking about weather, go with the 13 oz. sunforager. Get a smoke hole installed at the time of purchase - be sure you know what size stove pipe you'll be using, 5" is a good size to go with. You can pick up a nice wood stove through Cabela's that will do a good job for $150.00 complete (stove, pipe, damper and spark arester and removable ash drawer). You can always go with one of the propane type Mr. Heaters that are on the market now as they make them for enclosed areas.
No, I do not own a one pole - I have a 10 x 12 wall tent, a wedge tent and 4 diamond shelters, all of which are used differently, depending on what I'm planning on at the time.
Honestly for hunting - a wall tent will provide comfort that you won't get in the pyramid. They have been used for years by many an outfitter and have proven themself.
Hope this helps,
Wart