Welcome to the forums from the Netherlands, and thank you for the great introduction!
Yamaha bikes are the most reliable in the world, so your engineer friend did not advise badly
And the 650 is really a gem, beautiful looking bike too - the proportions seem just perfect. The 650 is substantially heavier than the Honda is, and has a lower point of gravity, so it would handle differently indeed.
What you may want to look into is changing the handlebars, or ad a set of risers - that may make all the difference. It certainly did for me on my Yammies. It seems that with the cruisers, the handlebars are just a little too far away from the right seating position for most people.
Get your dealer to help you with this: sit on the bike, close your eyes, sit comfortably and hold your arms where you would like the handlebars to be, where it feels comfortable. It likely only requires a few inches here and there, but it'll make a world of difference, I can assure you, both in comfort, and in handling.
Kind regards, Wim