The Ravenna 26 is a lovely instrument, but while it’s very portable as floor harps go (it’s definitely not a lap harp) it’s not the word’s greatest travel harp.
Though, to be honest, if by “keep your fingers in shape” you just mean keeping them nimble and not entirely losing your fingerings, there’s really no reason a Harpsicle wouldn’t do.
Again, Christina Tourin (http://www.emeraldharp.com) may be able to help you, as she often deals wtih used lap harps as well. Way back when I got my harp, she said she could likely match me up with someone who is selling a used one too, but I decided to buy a new one instead. She can also advise you on the Harpsicle and how it compares to other lap harps.