I’ve customized my 650 as well, using that site. The MyHarmony portal / app makes it easy, that’s been one of my favorite features of Harmony ownership. On the “Ultimate One”, the logos are auto-magically populated when you set up your program guide (I love that).
Like you, I also had a vintage Harmony (a 200 series). Dug it out of a drawer after years of non-use and it still works like a charm. Having since upgraded twice, I still like that old 200, and I really like the 350.