Kevin, welcome back. My wife and I both have carbedT100's. Both have been modded with freerer flowing exhausts and then rejetted to compensate. Rocky pretty well nailed it. You are familiar with carbed bikes, so the carbs will not be a challenge to you. The Bonnie will be tame after the Triple no matter what you do. The bike you are considering already has a modified exhaust and has most likely already been rejetted.
EFI will be more efficient. Will it be $2000 more efficient; I have my doubts. You can buy a lot of petrol and carb jets for $2000. Rocky mentioned starting which will be easier with EFI. The carbed Bonnies are cold blooded and do not like starting in cold weather. They start easily enough; but it requires the right procedure. It is not a big deal. Mine has never failed to start even in near freezing temps.
The Hinckley carbed Bonnies are nothing like the Meridan vintage Bonnies. There is no maintenance other than balancing the carbs once in a while. I check the balance every 12,000 miles or after rejetting. In 26,000 miles I only had to adjust the balance once and it was barely off then. I have never owned an EFI bike; so I can't really compare EFI. I am quite comfortable with carbs. For $2000, I would take the carbs. The downside to me for EFI is that any changes to the exhaust flow or intake flow require a computer to remap. I don't have the computer program and I know how to rejet.
As for the seat, as Rocky said, a King/Queen seat is much better for two up riding. However, there is a much cheaper alternative. Our own Poosta, who is an Aussie, sells custom made lambskin seat covers made by his wife. Both Mae Lyne and I have them on our bikes as do several others here. Those covers make an unbelievable difference in comfort - especially on long rides - no monkey butt - and they are cooler in the summer and warmer in the winter. I used to just put mine on for trips. It has not been off my bike in two years now. I recommend them without any reservation. They even make a custom rain cover to go over the seat.
I think you will enjoy the Bonnie; but it will be nothing like the Speed Triple. I have put almost 27,000 miles on my T100 and I put 13,000 miles of the 22,000 on Mae Lyne's.
