I like the looks of the fxdx-t factory bags, also. Plain and clean. I also like how they're expandable.
I found a used set on eBay a couple of weeks ago. The seller was asking $2300!! I thought it was an error, so I asked, and the seller told me she had previously listed them for $3000!! According to her, she saw a set sell for $2300, so that must be what they are worth. They didn't sell, of course. I was going to offer about $250 but didn't bother.
Instead I went to my closest friendly HD dealership, who let me brings bags out to my bike to see how they looked. In my opinion, on my FXDX, the TBU650 T-bag looked the best by far. The size, shade and texture complements the Harley crinkle black perfectly, and looks factory stock. I didn't care for any of the other bags I tried because the blacks were too light (more towards very dark gray), or the texture or the shape/size looked mismatched. Of course that's only my opinion for my bike.
So I bought a luggage rack (crinkle black) and the T-bag.
Just a thought and another option.