While I agree that if you've properly used lethal force, a prosecutor isn't likely to come after you if you've used a gun with a mag safety (or other "safety" device) removed, you can't PREDICT what the other party's attorney might try to do in a CIVIL SUIT.
There was a lengthy discussion on this topic recently, either here or on THE FIRING LINE, and one of the moderators -- an attorney with some knowledge of the topic, made the point that civil suits are different: the laws are different, the standards of proof are different, and things aren't nearly so clear cut when a gun is used. Unless your state's laws directly addresses the issue and shield you when lethal force is properly used, you can still end up in court. Judges may not understand or appreciate the fact that many guns don't have mag safeties, and most jurors won't care... particularly if the other attorney tries presents you as some kind of gun nut or cowboy.
More importantly, even if the other party loses their case against you, it will likely still cost you serious time and money. Attempts to recover some of your costs from the other party may be very difficult -- even if you get a judgment against them.
Since that discussion I've decided that I'll never use any of my "modified" guns (like a BHP with the mag safety removed) anywhere but the range, and I'll use only totally stock guns for carry. (For home defense, I'll probably grab whatever's at hand -- but that'll probably be a Glock 38...)