Just keep the bitcoin address seperate from your main address and you would be fine. No cross transfers from your main address to the bitcoin address you use for tipping.
I still think, direct tipping to a seperate bitcoin address should be the norm.. but for the people who do not care about anonymity, Changetip is fine.
You could also use mixing services to help you with the odd deposit you make for tipping. When the fee's become a issue, people will leave the service, it's as simple as that...
Lucky for us, these fee's are currently not a issue, because they are in the building phases..
