2 part doesnt really 'look' better per say, but it works better. It'll hold up longer, and be a little more resistant to heat, moisture, etc.
I talked to a rep that comes in to order supplies at my work, and she said they have a 1 part sealer (which can be used in any old caulking gun), that's pretty much identical to the OEM seam sealer around pinch welds, etc. So that would probably work decent for you as well, though i do not have any experience with said product.
I'll get a part # this weekend, or early next week.