It's an impressive ROF, but it's not really true to the real weapon you are attempting to emulate; more like a 9mm SMG's ROF, such as an UZI or a Skorpion maybe. Both the light and the heavy SCARs do have quite high rates of fire, but yours looks around twice the ROF of the 5.56 SCAR to me. The heavy calibre SCAR is noted for its compensator and stock etc making it seem like a much lower calibre in terms of the recoil and barrel climb that it transmits, but even so, I think if it was pumping 7.62x51 rounds out at the rate yours is, you'd have a hard time keeping it on target (not to mention probably melting the barrel), as in spite of the SCAR heavy controlling recoil better than older weapons and dissipating heat quite well - thanks to its more modern design - the fact is, 7.62 weapons do still take some controlling and fire discipline when on full auto.
Of course it's your weapon, you can have it fire how you like, but personally, I prefer it when my airsoft guns have some parity with their real firearm counterparts, i.e. I would want an AK to be doing somewhere around 600 rounds per minute rather than 6,000 lol. I'm also more inclined to fire on semi, usually relying on a three round triple tap, which I find is just as effective at keeping people's heads down or hitting them as letting half my mag go would have been. It's why even though my GBB MP5K has a ridiculously high rate of fire on full auto, which is admittedly fun to demonstrate (It can empty the standard 20 round mag in less than a second on full auto, so even the longer 50 round mags I have would hardly be that practical either). Thus I would find it totally impractical as a weapon for CQB skirmishing (which is what the MP5K is supposed to be for) if I did not prefer to shoot on semi-auto as most SWAT and SF teams would also do.
So I think that high ROFs are more use for a p*ssing contest in the test area where your gun is being chrono'd than for practical purposes, since in a skirmish you're either on target when shooting or you're not, and if you're on target and people are taking their hits, then one round is as good as twenty. But, above all, airsoft is about having fun and doing what you enjoy, so if having a Minigun's ROF on your assault rifle is what floats your boat, then so be it.
