All of my bags are shoulder bags except for my Speedy, it is simply not as impractical as it may seem.
I walked around with my husband for 2 hours today, carrying my stuffed to the gills Speedy- no problem whatsoever. On super busy days, I love it; it is so easy to grab and get in and out of the car, and as mentioned it fits a TON, yet has such a small footprint that it does not take up much room.
My advice would be to get one and try it out for a few weeks. If you decide it's not your cup of tea, sell it here on the Marketplace, it will be snatched up in a heartbeat.