There really isn't any extra maint with the 07-12 RDX Turbo compared to my TSX. The RDX requires Mobil 1 syn oil; but, I switched Mobil 1 for my TSX after my first oil change. The only extra thing I have to do is change the oil in the transfer case and rear diff 2-3 times every 100,000 miles. Other than that, same maint schedule as the TSX (rotations, fluid changes, filters, brakes, spark plugs, etc..).
The RDX is shorter in length for easy parking/maneuvering, takes 10-15 mins to put on a trailer hitch for cargo tray or bike rack, option for a roof rack, more leg room, wider cabin, waaay easier to fold down seats for large/long cargo, has better 360 degree visibility than the TSX, back-up cam, updated tech, sh-awd, larger 2nd row/cargo area, flat 2nd row floor for true 3 passenger comfort.
The only downsides is mpgs of about 18.5-20.5 mpg combined for my daily commute, 5AT can slow down the fun sometimes, and the ride is real "sporty" (which I love). The best I've gotten on the hwy was 22 mpg at 80 mph (+5000ft also).
I added the Hondata reflash for $300 to add 26hp/33tq and it made the RDX even easier to drive with a slight bump in mpgs. I later added ETS intercooler, heatshield gasket, K/N drop in filter, progress RSB, and Eibach springs. About 280-290hp/300-310tq with mods; which, has an added benefit of bumping up mpgs from 17-18 mpgs stock to the 18.5-20.5 combined mpgs with mods.
I've always been a sedan guy for +20 years and never considered a CUV/SUV. All it took was a few minutes behind the wheel, having a lot of TQ moments away, and the RDX is my favorite daily driver compared to my TSX and MDX.
Son - 06 TSX 5AT w/ Navi, Carbon Gray w/ Quartz (handed down for 16th B-day Mar/14)
His - 08 RDX Tech, Moroccan Red Pearl w/ Taupe (finally replaced Takata airbag on 6/16/16 after 86 days with rental)
Her - 11 MDX Adv/Ent, Palladium Metallic w/ Ebony