I used to occasionally travel with my Hasselblad (usually I travel with my Rollei TLR) and didn't find it too bad. It's quite a small, square kind of shape and I found that fairly easy to pack into my normal bag for the day. Even weight wise, I didn't find it to be at all heavy, even though it weighs a fair bit more than the Makina.
When I had the Makina, I found that although it is small folded, it is still too thick to easily squeeze into the kind of space you might have spare in a bag. Plus, there is rather a lot of vibration when the shutter is released (not sure if that was just mine of a general thing) so the advantage RFs have in hand-holdable slow shutter speeds was partially lost. It was also rather slow to use which I found to be a disadvantage as much of my travel is work/study related so I need to be squeeze photos in when I see something on the way to a conference/train station etc. The last reasons why I preferred the Hasselblad is because I like to take close up photos a lot, and just needed to slap a proxar on, no chance with the Makina, plus I prefer 6x6.
That's why I'd keep the Mamiya and the Hasselblad, one very light camera and one for close ups and careful framing. Though really, I think a lot just depends on personal style/preferences, and bear in mind I really didn't like the Makina at all.
Just to put my objective hat on for a moment, there is an argument for selling the Hasselblad. If you in the end decide you miss it and want to buy another, they are ten a penny and will almost certainly be cheaper than when you sold it. Makinas and Mamiya 6s seem to be much thinner on the ground.