Frank, I just visited Swenson's Gardens (west of Minneapolis) yesterday, on their first day of this year's Field Days. (Is this the same as the Svenson's you ordered your Itoh's from?)
I will receive my first plants from them this fall, so I can report on those next year. I ordered one Itoh, 'First Arrival' and 4 more, 'Candy Cane', 'Sprite', 'Coral Sunset', and P.officinalis huthii. The thousands of peonies I saw in their fields were spectacular! Here is my absolute favorite of all I saw:
Itoh peony 'Purple Flash' unfortunately for me, not available for sale
Regarding your Bartzella, I wonder if Park Seeds is offering tissue culture plants... I've heard you may have to wait years for proper development of tc peonies?
I got my 'Bartzella' in 2011 from Tony Avent's Plant Delights Nursery, and I couldn't be happier with it. It bloomed in 2012, but even more in 2013. This year I am almost speechless when I look at it!
I can't seem to get proper color of yellow or white when I take distance shots, but it is bright yellow!
I get better results with close-ups.