Considering that for defense you are NORMALLY talking about close range, you might consider if slugs give any real advantage over buckshot.
Effective range of 00 buck- about 30 yards. Effective range of slug- about 100 yds. Slugs will penetrate more than buck- can be advantage or disadvantage. Somebody in the front hall- buck. Being shot at by someone in a car- slug.
If you shotgun is a smoothbore, stick to rifled slugs. Sabot slugs are intended for rifled barrels, and from a smoothbore, will travel pretty well wherever they please.