The 7.0 Engineer was a step in the right direction and a halfstep backwards.
I love the engineer tools list and I can even live with his robohorse and it's electrical brass balls. I have to admit I sort of like the model too! (/me ducks for cover). That being said I think he needs some adjustments to be truly worthy in the field. So for all intents and purposes I'll suggest keeping him as is with some exceptions.
Ballistic Skill 5. - The Engineer has been creating and firing weapons since he was a wee lil lad. It's not hard to imagine that he served as a handgunner in an Imperial army somewhere and eventually was promoted to lead a unit. It's also not hard to imagine his skill in calibrating and firing a war machine with dead on accuracy. He should be one of the best shooters on the battlefield, and his enemies beware, an engineer with a hochland long rifle will be taking shots on your noggin. Had the GW design team reasoned this, the Engineer would be fielded much more on the table.
Reroll Ability- If an Empire Engineer is on the table, ALL warmachines get a reroll in case of a misfire. His coaching and efficiency amongst the war machine crews prior to battle, and on the warpath have boosted their abilities on the field. If an Engineer crews a War Machine, his BS is utilized when necessary, and a second Reroll can be applied in case of a misfire.
-Grutch