We returned last night from Russia.
Changing to the Peterhof was the best thing you could have done. This boat was recently upgraded and the rooms are larger.
The regular size rooms on the Kirvo are almost unbearable. The bathrooms are ~3' X 5' and the sink facuet is your shower head!
Everything else was GREAT, including food, tours, service, etc.
Our Tour Company, DB tours, had explained everything it detail prior to the trip. The saved us big bucks and knew every detail of the trip. Where to buy items and how to negotiate.
let us know if we can answer any other questions.