As a serving elder and occasional poster here, I have been watching with growing horror at what is being done. Here in the UK, we haven't had any letters since the original one read out to the congregation and in particular nothing saying we can only retain a certain amount. I suspect that the charity laws here are proving to be a bit of an obstacle (never thought I'd like red tape) but I'm sure the branch are working on it - maybe make it a "suggestion" then enforce it during the co's visit, maybe change the congregations constitutions (could be messy) or maybe water down the instruction in some way. For the record, all my cong has done is to modestly increase its regular donation. No slips handed out. No mention of sending a one off donation.
If (or when) the new arrangement comes in here, I'll put my arguements against it, but ultimately I agree 100% with Outlaw - I'll resign.