Being Armour, which I am naturally biased towards, I wonder at you logic? I know that Engineers do lots of things, but I highly doubt a Reserve Engr unit will offer you much. I don't think you will honestly see any opportunity to use any Heavy Equip (actually operate it) while in the Reserves. Perhaps you'll have the opportunity to in close proximity to it on a tasking to the Reg Force or on Exercise, but unless you have a CF qualification, even if you operate one on Civie Street, you are not likely going to be able to touch it.
As for transferable skills from Engr to Inf, I can not think of very many. If you go Armd, you'll definitely be getting Driving Courses and a Military Lic (404) in order to do your job. You'll pick up Map Using and Navigation skills, Communications skills, Weapons handling skills on numerous weapons, become familiar with Tactics and will be more likely to be out using these skills in a combat related role. These skills would be much more transferable to the Infantry than learning how to use C4 (which is not in the Infantry 'inventory') or how to use Heavy Earth moving machines. If you intend to become an Infantry Officer, I would suggest the Armour route.
Besides, it is a change from what you do everyday at your current job - or are you afraid of something different? Some Change? ;D