First, don't worry about the dealer. They know you gave them the first shot and they know that they couldn't get you what you wanted. Believe me, they will still be happy to take your service dollars.
Second, if you are looking at the Ultra for everything that comes with it, like tourpack and rear speakers, etc., then you'll miss those items with the SESG. If you are planning on removing the tourpack and rear speakers, and making it look like a SG, then why spend the extra on the Ultra? As much as I like the SESG, I don't see it as a substitute for the SEUC.
If you want the Ultra, don't keep pondering it. If you don't act quickly, it'll be gone. Someone will scoop it up if you don't. I was lucky that when I bought mine, I didn't think twice and immediately said I'll take it. Five minutes later, a couple walked in with a checkbook in hand ready to buy it and they were 5 minutes too late.