In my mind UTX is absolutely essential to the FSX experience (except with photo-real scenery) due to the shorelines, roads and waterclass. GEX also has a lot to offer. With that said, there will be instances where the landclass around an airport will be less real with UTX and GEX than with the default scenery. UTX adds urban landclass where left out of the default scenery, mostly to the good, but sometimes where it doesn't actually exist around an airport. GEX includes some autogen commercial buildings (including some high-rises) in suburb landclass. This is good, except sometimes this adds a high-rise building at the end of a runway which is hard to negotiate on landing. Fortunately with tools like ADE, anyone can make the changes necessary around airports they frequent.
MSI P55-CD53, Intel i7-860-3.7Ghz, NVida GeForce 560 - 1GB, 4GB SDRAM DDR3 1333, WD 750GB-7200rpm-32MB, Windows 7-64 bit
Acer 23"WS LCD and Benq 19" LCD, CH yoke and pedals, Logitech Extreme 3D Pro, TrackIR 5, FSX Deluxe w/Acceleration, UTX-USA, GEX, ASE, WOAI, ADE, FSDS