You specifically said "acute" pain, which to me is a discomfort usually involving an injury which needs immediate rest (although usually a short period).
However, the problem remains that pain is completely subjective.
While I do no necessarily condone being greedy with your body when it comes to pain, I can appreciate the fact you want to train through it. I would limit yourself to the following conditions (just my opinion):
1. If your stride changes or is compromised in any noticeable fashion, stop running and get on a trainer of some sort.
2. If you begin your run with a certain level of discomfort that raises only 1-4 points on a scale of 0-10, then keep running to toleration.
3. However, if that discomfort level raises past a dull ache or slight weakness and pushes you above a 5/10, stop running.
4. Sharp pain or stabbing that does not start to go away within first 5 minutes of run = stop running.
5. If you feel excessively worse after you stop running or the next morning (i.e. area gets very tight, burns, loss of ROM, sharp pains) then chances are you should stop running because in another 9 weeks it's not going to feel pretty.
Bottom line is "groin pain" can be a MILLION problems and a large amount of the time the pain is radicular and may not even be stemming from your groin. It could be coming from your SI-joint, hip capsule, pubic symphysis, etc. The smartest way to treat your body is individually.
My last bit of advice is if you have a marathon log, log your pain level for that day and exactly what hurt and how it hurt during the run. Log improvements/problems that are new. That way, you can take note of any trend. One of the worst problems with injuries that tend to creep into the picture is you have a chance to adjust mentally and physically to the pain and tell yourself it's not getting worse.