I registered as a democrat here in the SF Bay area. Partly because I want to keep track of the other side, but mostly because I don’t want to experience mysterious problems with voting. I have never had trouble voting, getting sample ballots in the mail, showing up on voter rolls, etc. My wife, as a registered Republican has never received anything in the mail, has not shown up on voter rolls many times, and nothing has changed despite registering to vote several times.