Davidsans is in 5b (though almost zone 6), and here's what he has to say about it:

It is a fav of mine since it stays really small most get only 1 ft in 10 years and stays stiffly compact with short stems and small leaves and is hardy.. One of the best dwarfs around .but hates wet feet and needs some shade.

He typed it as Hubbs Dwarf, but I see quite a few typos on his site and I'm assuming that's one of them. The photo looks like Hupps.

Here is a link that might be useful: Hupps Dwarf

I love mine, too. I'm in 7b, though, so I have nothing to offer you about Chicago.

My .Hupp's Dwarf is about 5 years old and yes, it's only about 16" tall. However, in full unmitigating, horrendous sun this year, it's put out 2" of new growth on two stems. Lovely pinky leaves.

I wish you luck with yours!

Thanks to both of you for the follow ups. I'm on the fence after losing my Kamagata last year. Hupp's would be reasonable to protect each winter.

I pulled the trigger, wish me luck.

Thats Hupp's Dwarf? That tree would have to be close to 20 years old or no?

I'll have to defer to someone with more Pacific Northwest experience. It came from Don Schmidt in Oregon, the tag was still on it at my garden center.

According to Don Schmidt's site, they grow on 7-10 years cycles. I'm assuming that it means that it's 7-10 years old?

The size is one reason I had to buy it. I would tend to think that a small graft would take close to 20 years to get to that size in our neck of the woods. The trunk above the graft is a good inch and a half in diameter.

I plan on covering with leaves late in November and removing them in late February to give it a chance.

Maybe you have Kotohime

That doesn't look like my Kotohime at all, but does look exactly like my baby Hupp's Dwarf.

That tree is gorgeous! I can't wait to see mine grow like that. Mine is probably 5-6 years old. I'm so happy to see yours of such size.

Good luck with this beauty!

Was just thinking about the "covering it with leaves" thing and then removing them.

Leaves decompose into wonderful, rich earth. Why remove them? Just make certain there's room around the trunk so it can breathe. i.e. moisture isn't held against the trunk.

Your picture has me encouraged to put mine in the ground. I need something small to go into a bed, under another 40 year old maple, where I just yesterday dug out some extremely mature hellebores. I'm thinking my Hupp's! But, would it survive the adult maple's roots...?

But then, there's my Cynthia's Crown Jewels, Geisha, Fjellheim, Skeeter's Broom, Shania, (stop me!)

Anyway, I think I'm gonna give 'er a try.

About that overwintering thing. Don't be shy about keeping it in its pot over the winter, but burying the pot in the ground in a protected spot. The leaves again, are a good cover.