The 15-90 is a great machine. Think bullet proof. They also have a bigger harp space than your 301 and they're great for FMQ. Extra bobbins are also dirt cheap compared to a 301.
Try the knee control. Personally I prefer a knee controller over a foot control. Also look at it, sometimes the knee control is actually a foot control in a special bracket that you can just unclip and use on the floor if you prefer.
If this doesn't talk you into keeping it is there another active sewer somewhere in your family that would like it to keep? Or possibly a grand child, niece, nephew, whatever that wants to learn? Maniac's idea was a good one. It would be a shame for it to leave your family after being in it for so long.
Rodney