Bikeliot.
We have had our D1 Diplomat up and running, for just over a month now. We had similar concerns on the layout, and also didn't care about stereo, and waterfall features. And like you, most of the time, it is just the two of us using the tub. And although it's only been one month, the maintenance so far has been very simple as well.
So far, WE TOTALLY LOVE IT, and have had no complaints. We love the his/hers loungers - and each of us use "our seat" 95% of the time. The pillows with the neck jets are fantastic as well. Neither one of us has had any floating issues, and have found the tub to be fine for having a few extra people in as well. We've had up to 6 people in it, with no space problems, and no shortage of space in the footwell. And given how much I HATE feet, I would be honest with you if my tender tootsies had touched anyone elses....
Wet-testing will confirm that the tub fits for you, and like a few others have said, ensure that there will be good service and warranty follow through......
Good luck, hope your wet-test goes well! Please let me know if you have any questions...
AlpineGirl