Is there a reliable way to

determine strength imbalance?

I would be interested to know if anyone knows what the ratio of back-to-chest strength would be.

I.e., if I can do a 100-lb bench press, how much SHOULD I be able to lift with a bent-over row?

Best educated guess?

It should be close to equal, With some of my clients I super set dumbell bench press with a one arm row using the same weight. Some times with the bent over row the low back becomes the limiting factor with higher weights. Strength imbalances aren't that bad, think of a pitcher in baseballl there are going to be a huge amount of imbalances due to the nature of his sport. Yes it is possible for an imbalance to cause injury but lat's vs. chest is unlikly.

I've actually heard that if you have bad posture it's a sign of muscle imbalance, so that might be a good starting point

I am more curious than anything else. A one-to-one ratio seems OK to me.

Would you aim to get your clients at this ratio?

I'm certain that being a little off one way or the other shouldn't be a problem.

chest vs lats imbalance can cause injury to shoulders if i'm not mistaken. Rounded shoulders are a sign that chest is too strong vs lats.

actually rounded shoulders would mean Overdeveloped lats. the lats internally rotate the shoulder. this could also mean a chest that is too strong or too tight, and weak rhomboids and traps.

Like I said muscle imbalances are not important to me.

I've never seen a shoulder injury caused by a chest v. Lat imbalance. I have an imbalance of roughly 2 to 1 (bench vs. Seated row) and I don't have any related shoulder injury. Rounded shoulders is caused by lazy posture and can easily be fixed.