patched higher difficulty

ME:A is super easy in NG+, even on Insanity.

The problem with a question like yours is it becomes subjective to how a person views the content combined with their build and skill level.

If you are nervous that it might get harder you could just do what you think is mandatory. In my opinion the primary story mission and probably the ark missions would be the most important. I have been told there are a few side quests that will also impact the final stretch of the game I cannot tell for certain if they do or not or just change dialogue. The majority of the quests aside from some on the Nexus are playable post the end of the main story line.

Edit:

You can always drop the difficulty if you find it gets too tough as well unless you are only doing it for the achievement for beating it on insanity then would I just do more of a hurried play through if you are concerned.

OP asked are enemies overpowered in NG+. I simply stated opposite is true, they're too easy.

Thank you kindly for your answer. I have a strong build, and I'd hate for it to become less powerful as I grow.

Enemies started scaling massively at high levels in NG+, while the player's power reached a bit of a cap at this point. So the game just became progressively harder with few ways for you to catch up.

Unfortunately the nerf made all of Insanity easier at once, which is a bit of a shame as I liked its difficulty. Then again it did make some enemies lose their bullet sponge status which is fine by me.

I'll take DLC 'trials' modes and/or much more difficult scenarios.

Well it all depends at which level you finish the first playthrought