rotorspeed,
Provided ATC know what to expect - the call is immaterial.
The Flight Manual always contains the conditions under which engine limits may be used. The only short term OEI limits that I am aware of are the 30 second plus the 2 minute limit - or for those which do not have a 30 second limit, the 2.5 minute limit (note that the AB139 does not use a 30 second limit - presumably because it is not required).
A rejected take-off is unlikely to come anywhere near that time - unlike the continued take-off where the limits have to be observed and not exceeded. One of the problems seen in the recent past is the reluctance to pull up to limits by drooping the rotors on a reject - with the consequence of an increasing rate of descent and a hard landing. Fortunately most of the occurrences were in training and not during operations.
Depending on the engine, the use of the 30 second limit might result in maintenance procedures (I think that 212man has had something to say about that in the past with the EC155) but is unlikely to have a severe affect on the gearbox.
Whatever the consequence it will have been pre-considered by the State of Design and the Type Certificate Holder and have been part of the certification process - and addressed in the Flight Manual or the Maintenance Procedures.
Most of the profiles/procedures that I described in my last post and PC2e (offshore zero exposure departures), benefit from the use of FADEC (which protects the remaining engine and the transmission) and the stored energy provided by the additional NR.
There have been discussions on FADEC limit override but I am not aware that this has led to changes to FADEC algorithms - that and blow-away power are really tools of last resort.
Jim