Have all my policies with the same carrier..
another interesting "quirk" here in my state...it is rare that a carrier would want the home AND auto/boat. Most auto/boat carriers want nothing to do with homeowner policy. The home carriers are undercapitalized and therefore can't take boat/auto in many cases... so you pretty much get screwed out of the "multipolicy discount" some offer.
There was a "race to the bottom" in auto coverage a short time ago, and plenty of SR-22 coverages out there which is why you should really make sure you've got good UM/UIM coverage. FL only requires $10,000/$20,000 liability, which would just about cover a damaged bumper on many cars here.
In the Peoples (soon to be bankrupt) Republic Kalifornia if you want to sell auto policies you need to do the other policies as well.. May be a good thing, maybe not!
I hear ya on the UN and under insured motorist, got the max on that and have an umbrella policy as well..
Found it odd that when your boat is hooked to the car the auto policy covers it, when sitting in the storage yard, the homeowners policy covers it, when it is on the water, the boat policy covers it... Needless to say, I have the max on all three..
Been sued before and I won, but it was not fun and it is a comfort to know I was covered should I have lost...