I think the hardest part of using multiple machines is the reverse. My Juki has a BIG up/down handle sticking out on the front for reverse. My Janome uses a button. And my Elna uses a left/right lever. I do fine until I have to use reverse. 15-20 minutes into a session on these machines and I am fine. I never have a problem switching to a serger. I guess my weak little mind somehow processes the serger as a completely different activity.
I wouldn't worry about getting a travel machine. Chances are you will quickly learn to love the one you're with!