Given the recent nerf (well, technically fix) to super elixir, I think that having tried it when it was buffed that it made the engineer great for seconding his role as a healer and otherwise increasing the survivability of his teammates.
I would like to request that a compromise be reached between the recent nerf and how strong super elixir was when it was mistakenly buffed in order to augment the engineer’s utility as an off-healer.
The best way to do this, I believe is to increase how well that healing scales with most skills, most notably super-elixir and perhaps regeneration abilities (like tossed elixir h, healing turrets, etc). This would add further versatility to the engineer by allowing them to see a real difference from equipping armors and accessories that increase healing power (usually at the expense of attack power).
Care must certainly be taken to ensure that it does not cause problems with bunker builds in sPvP, but if that care is taken and healing could scale a little better I think that would go a long way to making the engineer what it is supposed to be ‘a highly versatile class’.