Judging by the little information we have, that 250nm test (against a ground target) was more of a missile RAero rather than Rmax, so it is almost impossible that an air target could be engaged on such a distance (still can increase range for ASh SM-6s). Besides, they used guidance from other vessels, a thing that is notoriously absent from DCS (to be honest, the whole way sensor and weapon guidance logic works here makes any Aegis simulation... extremely arcade. No AESA multi-tracking, no problem with terminal AN/SPG-62 guidance bottleneck, etc,etc). In-game Tico radar gives 200nm detection range against aircraft (Burke has 240) which is waaay better than RL ranges (at least from open sources). And ground targets are capped at 100km (~50nm). So, expanding range to AA SM-6 will turn them into wunderwaffe (and also will be much less realistic that the numbers we have now due to the whole sensor thing). And making AShM SM-6 250nm would require expanding SS radar range to 250nm which in turn can break a lot of other things in unit logic. So... not really worthy.
Sadly, in DCS we always have to compromise between realism and game engine limitations, and I think CH got it right in case of SM-6s.
Anyway, SM-3s still break realism and engage lofting ASMs (like Tu-22M X-15s) at 25k+ while in reality they are purely exoatmospheric. But since DCS engine has problems with exoatmospherics and missiles have to "flatline" themselves, you again have to compromise.
I tampered with the config file just a little (hope Currenthill will forgive me for this ahahah) testing SM-3s with their H_min set progressively to 30k, 40k, 50k - and I still have no coherent answer as to which one is better (personally just for me, I think 30k will do a bit better but still).