Twinject was scary! I suppose it would be all fine and good if you were calm and coherent enough to administer a second dose, but there is no way I could do it on my own. I can barely manage the automated injection on any device. I always opted for two EpiPens. (Though I know a few people who carried two Twinject instead, two for themselves to use if needed, or up to four if a bystander was able to give the syringe dose.)
Emerade is good if you need the longer needle or higher dose, I suppose. I don't fit into either category but know many who do. I wonder why it isn't available in Canada. (I can think of a few reasons, legal stuff and all.). I think it is available in parts of Asia as well - or another similar device is.
Still waiting for Allerject to return to Canada... And trying not to be jealous of all you Americans with Auvi-Qs. Audio cues and the size... I dream of the day.