Gary,
Brilliant minds must think alike (or is that 'fools seldom differ'?)
Anyway, I just picked up a DX18 too as an upgrade from my DX8. I've had it just over a week. So far I'm real pleased with it, I don't see myself using most of the channels as I'm stuck with small to medium size models for the foreseeable future, but some of the features are very nice. For instance the mixes with multi point curves should come in useful for some of my planes that need lots of mixing, and inbuilt data logging is cool too, though you could do it with the DX8 with 3rd party software.
I've flown a few models and my heli with it, it felt a little different at first but after two or three flights i was totally comfortable. I figured out after flying why it felt different; the gimbal housings on the DX18 are angled slightly so that in the neutral position the sticks too are canted out. On the DX8 gimbals are mounted flat to the face of the Tx with the sticks perfectly perpendicular. The outward facing sticks do seem more ergonomic and it reduces the reach when moving sticks toward the centre of the Tx.
PS... Best upgrade to latest firmware BEFORE programming in your models because the upgrade wipes out the memory. If you have programmed and want to upgrade all is not lost. Export the models to your SD card, upgrade, then re-import them.