Forgive my complete bias here, and it's not a brand thing.
I have looked extensively at the new radios in the $1500 and under price range.
My feeling is that if you love Icom, and have wanted a IC-718 for years, and it will make you feel fantastic to own one, then by all means buy it.
Short of that scenario, there is no comparison between the two radios.
The FT-450 is a brand new technology radio, incorporating tons of features not dreamed of when the IC-718 was designed.
Outside the giant list of features the FT has that the IC doesn't, I can also think of some more practical reasons for the FT-450 getting the nod.
1) The FT has 6 meters. Get a taste of 6 and you will want to have access to it frequently, I promise.
2) The FT can be run mobile after you get your "big radio".
3) If you don't dig mobile, you can work 6 meters and HF at the same time after you get your "big radio". If you like 6, you will want to have a radio running there all the time while you work HF on another radio.
4) With the FT, you don't need to buy filters. The 1.9K SSB and 500Hz CW filters for the IC will set you back $400 for the pair.
At Universal Radio ( http://www.universal-radio.com/catalog/hamhf/0450.html
) you can get the FT-450 with the antenna tuner installed for $749.95.
The FT is kinda ugly, but somebody show me a better value under $800.
Graham Welch - K5PEW (In memory of Paisley Elizabeth Welch)