Go for the long arm! You can always sell it if it doesn't work out.
Look at it this way, you are investing in a move and a new house so why not a new toy? And as someone else already said, if not now, when??
My mom is 83, the women on her side of the family all live to be 90-100+. I tell her that any medical condition or thing she wants, she should figure she has ten years so is it worth fixing/doing without for those 10 years? My answer is if you can afford it, no. You've spent enough of your life on other people so buy this machine for you. And splurge! Get the computer driven model if you can afford it even if you end up not using it the time to get it is when you buy your set up and not as an addition afterwards.