Do you have a rolling case you can use with the Singer? I'd only get the 301 if I could drag it around on wheels - especially with problem shoulders.
The Janome Gem weighs less.
The Singer will last forever, but your shoulders may not if the machine is too heavy for you.
And this is coming from a fan of old Singers!
My take-along is a Babylock-9, simply for ease of transport.
Good luck with your decision.