Finished rereading a few weeks ago because my younger son, the 10-year old SF lover, was interested. I couldn't remember the story well enough to decide whether it was OK for a soon-to-be 5th grader or included any of the triggers that my husband and I decided mean "save for later."
I think I would have liked The Engines of God more if I had discovered Jack McDevitt back in 1994 when this book first came out. Back then, I was reading more SF and less YA and Urban Fantasy. These days, I also find myself primarily reading SF/Fantasy written by women. I was intrigued enough by Priscilla "Hutch" Hutchins that I will be adding the rest of the series to my "read eventually" list. I'm not a particularly critical reader and didn't notice any errors of perspective, but wonder how Hutch would have been portrayed differently if the author was a woman.
In the end, we decided that my son might be a bit bored because there weren't any sweeping battles, but that Engines of God could go on his shelf of potential books to read. We were right, and while he read it, he hasn't asked for the sequel yet.
P.S. My son is a relatively precocious reader who has already devoured most of the YA classics, along with large portions R.A Salvatores Drizzt series, some of the Honor Harrington series, and just finished Asimov's original Foundation trilogy. So the fact that we decided that The Engines of God contained appropriate vocabulary and story complexity for him may not be typical of about-to-be 5th graders. The Engines of God contains several brief scenes where characters head off-screen for or mention satisfaction with implied "adult entertainment" but while we defer books with explicit sex this was subtle enough that we figured it would just not register.