You seem to miss the point.
I don't think so. Your thoughts are at variance with the certification philosophies upon which the performance numbers are built. Indeed, I would dearly love to have a beer or three with your instructors to discuss their views on the subject .. their reported position is a bit of a worry, methinks.
there is no law to state you must be at V2 but usually is V2 + 10/20 in order to achieve the required climb gradient.
I'm afraid it appears that it might be you who is missing the point and I have to wonder if your earlier training may have been a bit deficient ?
For line operations with FAR 25 Types, V2 is based on the OEI case and, unless there be a very good reason to do otherwise, it should be the OEI target for a failure near V1 - for faster than V2 failures, the better climb performance overspeed means that one prefers to hold the margin above V2, generally to a maximum of around V2+20.
If you are AEO (as is the usual case), the preferred technique is to rotate at the AFM (OEI) rate to the Type AEO pitch attitude and hold the resulting speed .. which, generally, is a bit in excess of V2. There is no "required gradient" AEO for the takeoff analysis although the presumption is that the aircraft will be operated in a manner which will keep the AEO flight path above the OEI AFM flight path.
define V1 as a "decision speed"
The design rule book has changed over the years. Hence it is essential to check the TCDS for Type to check on the certification basis (ie which design rules applied to the Type) before one starts looking up the design standards - generally, it is necessary to look at superseded revisions - easy for the FARs via the FAA website.
The V1 concept is no different and it has changed from the earlier "decision" speed idea to the far more practical present Industry approach which can be paraphrased .. "if you haven't already started stopping by V1, then you keep going". Clearly, there may be occasions where the Commander needs to apply his/her prerogative and stop but such situations are in the extreme minority.
The F27 is an extreme case. The original design was to the old design standards. Not all that long after the aircraft came onto the market, it was recertificated to the ICAO PAMC for performance. That report became the basis for modern design standards. Recently I acquired copies (courtesy of zzuf and OG) and, at some stage, will get around to scanning them so that folk who are interested in the design standards history might be able to read a copy. The document is not easy to find .. I have kept my eyes open for one for many years without success until the two good PPRuNe folk mentioned gave me their personal copies.