I understand the damage part of the argument and agree that bigger dogs do bigger damage; however, to say that ALL pit bulls, ALL Dobermans, ALL Boxers, etc are aggressive and dangerous because a very small percentage bit someone is ridiculous. Are ALL sportscars involved in an accident? No, that is why they quote you based on YOUR driving record/age/etc.
Let's keep all things equal, please.
Furthermore, you can still get insurance for a sportscar, it may cost a little more, but it's available through every insurer. It is nearly impossible to find a place who will rent to anyone with "an aggressive dog breed (Dobermans, Boxers, Pits, Rottweilers, German Shepherds)". ZERO. Most companies will not write you a home owner's policy if you have one. It;s simply not fair to lump them all together.