Hey Jeff u are making a great decision with vaping!
But the reason some talk in 300C and some talk 250c is because there was a earlier model that had the temp sensor closer to the element so it wasn't accurate regarding the temp of the herb, and ppl didn't like this. So arizer brought the sensor closer to the bowl so it would read the actual vaping temp. But the newer models stop at 250c which is perfect cause i have NEVER burned any herb at any temp with the extreme, which is one reason i like the extreme soo much(don't have to worry about ever burning your herb and getting nasty carcinogens). If you bought a extreme now you would get the newer, "better" one.
And the balloons are absolutely wonderful you can make the vapor as thick or as thin as u want in the balloon. I personally do the balloons all the time, if i dont want much vapor ill hit the whip occasionally. But all you can taste is the vapor!
The difference between the bag blowing with the extreme and volcano is the volcano can get to higher temps(it can be a pro or a con), temps that will burn the herb and produce thicker vapor but usually thicker vapor means its starting to com bust, and you don;t want that. Volcano also has a valve which is neat but unnecessary, i just use a cap for the extreme bags and its no big deal.
If i were you id get the extreme, its a lot cheaper and does exactly wat the volcano does so why pay another 300 dollars.....:/