Another option might be S & S couplers on your existing bike or a new frame.
Being able to rent a bike prior to purchase may save you both money and time.
One issue is if you like the ride of a particular bike; geometry, handling, etc.
Another issue is packing. Most bikes will have to be taken apart to fit a standard
sized luggage. I've bought 2 low end bikes in the past to do this exact experiment
myself; Tobukaeru w/ 20 inch wheels and a Citizen Tokyo with 16 inch wheels:

https://www.youtube.com/watch?v=eUQN...6zPoymgKaIoDLA

2013 Citizen Tokyo in a suitcase by 1nterceptor, on Flickr

In the end I found out I like travelling with my own bike. I didn't like breaking down bikes for packing.
So I ended up with the Brompton. The small size also helps when trying to go discretely to places;
hotels, restaurants, shops, museums, etc.

https://www.youtube.com/watch?v=yhZT...6zPoymgKaIoDLA