I second what Carl Lewis said about the Legacy but wanted to respond about the light stick forces/fast roll rate and IFR.  I frist flew IFR in Navy tactical jets which have comparable stick forces and roll rates considerably faster than the Legacy.  After that, for about 30 years, I didn't fly at all or flew bonanzas etc.  Because I had very little current time, I was a barely adequate instrument pilot and only flew IMC in benign condidtions (e.g. ceiling over 1,000).

The first time I flew IMC in the Legacy, I had an instructor with me.  We entered the clouds and, within 30 seconds, I was in a 70 degree bank.  I recovered easily and, with some effort of concentration made steady progress through the flight to the point where I was making pretty fair approaches by the end of it.  Thinking about it afterwards, I realized that I had to relearn IMC techniques that I had learned in the military.  Among other things, trim is important.  Make sure you have a trim button on the stick that controls elevator and aileron (you hardly ever mess with rudder trim) and keep trimming out even small pressures.  Trimmed up, the Legacy flies a more stable pattern throughout the airspeed range than any plane I have ever flown (including a Pilatus PC-12 which feels like a truck.)  That is true both in smooth air and light chop.  Because of the trim control possiblities with a stick-mounted system and the precise control input that is possible in the Legacy (control pushrods rather than cables) you can fly more accurate instruments in a Legacy than in any even remotely equivalent certified airplane.

Bottom line:  if you are used to flying instrments in C-172's, you will need to go through a transition while you get used to the more precise control inputs.  The transition should not take long, however, and, when you get through it, you will not believe what a joy the Legacy is as an instrument platform (as it is in every other respect.)  I join with Carl in urging you to go to Redmond and try it out.  You won't believe it and the speed is just the beginning.