If the data supports it, then you should use whatever you can eke out. Trouble is, garbage in, garbage out. We sometimes need maximum available derate, particularly on low RCR fields (talking of below 5 here) in strong crosswinds, as the DRT gives us a much better Vmcg. Not to mention,you get airbourne much closer to Vmca/V2 on derate departures as your rotate speed is typically 10-15 knots higher, particularly at light weights.
Reaction... before, or certainly past V1, we are now going flying. Lets apply full-power, manually (Firewall the trust levers) and get this aircraft into the air and climbing away. Sort out/discuss the cause later.
might want to reconsidert that, particularly if Vmcg is based upon your derated thrust setting. you are going off the edge if you suffer a subsequent engine failure past V1 with a vmcg issue and max thrust now set.
This all comes down to airmanship and the likes of gross error checks/independent perf calculations. Not sure the typical loco turnaround times would support that though...