Dynavap M7 vs M7 XL

The XL costs $35 more on POTV, I am leaning toward the XL as it has a longer mouthpiece, which seems important since I want to use it with a small glass bong. Or in case I use it by itself, seems like the longer xl version would be better so as not to get burned from the heat coming off the torch? Has anyone tried both to compare? I will also get the Solo 3, but I'd like a Dynavap as well, just need to know which model.