I can tell you from personal experience of opening and cancelling many (>20) credit cards over the past 20 months that scores for my wife and I have fluctuated in different manners across the 3 reporting agencies. Scores dropped with Experian which received the majority of the inquiries, but actually climbed with the other two agencies (probably because we have not cancelled every card since starting and the credit history keeps increasing on those that remain open). The low score with Experian was about 30 points lower for both of us than when we started, but for me has now rebounded to slightly higher than when we started since I have not had an Experian inquiry for several months now and I expect similar results on my wife's score since we've pulled back on churning Citi cards for now.

Since I can only pull our scores once a month and we were both opening and cancelling cards continously, I can't tell how much the cancelling of credit cards impacted our scores in the monthly fluctuations. Bottom line is our credit scores are no worse off now than they were before stumbling into this very addictive hobby almost two years ago.