I have a Benelli M1 Super 90 Tactical. It DOES have a pistol grip as well as a ghost ring sights and an 18 1/2" barrel.
The pistol grip is in addition to the regular stock. It is not a pistol grip only SG as several other manufacturers produce. The pistol grip only are very difficult to fire follow-up shots. JMHO.
My Tactical holds a total of 8 rounds of 2 3/4" shells. The only downside to this gun is its cost, which eight years ago was $900. You could probably buy two 870's for that amount and they would be my second choice as they're a great gun from what everyone says.
Safe shooting.