Have a KX-155 nav/com and an old garmin 250 vfr gps. Looking to swap out the 250 for a new 175 and replace my attitude and DG with G5's. Ditching the 250 means losing my second comm radio. When I emailed the radio shop asking about the install, the owner suggested that I would need to buy the 175 and a comm radio since I am round filing the 250. Are there any legal requirements about the number of comm radios available for IFR? I realize two is better than one but I carry a handheld backup and I really don't think a second comm radio is worth $3,000.