WieWaldi I think 88 keys is maybe too much for a traveling keyboard.
Maybe. But I really think a person has to ask the honest question; "Do you play the notes that would be missing on a 61 or 73 or 76 note keyboard?" If you never play them, the answer is obvious. If you do play those notes quite a lot, a shorter keyboard may not be ideal.
There are a lot of players out there who really may not play all 88, ever. I ain't one of 'em. I'd play 108 if they were available. There have been a whole lotta times I've gotten carried away with a run, in either direction, up or down, where a finger hit the wooden cheek block of the piano where a certain key would be if it existed.
Used to torque me off when I was tuning pianos. One of the "45 minute wonder" tuners would completely skip the top octave to octave and a half on a tuning and remark, "nobody ever plays those notes anyway". Um, yeah, some of us do. He had his list of faithful customers. There was another list of customers that said, "never send him to tune my piano again".