P2 extremes are best in problem pubs as a) they don't key and you don't need to know any balance, the landlords don't think you are winning much, and if you do, the auto dump facility and the ability to catch the money in your hand avoids any undue attention.
Reds are worse. They don't dump, they usually always go big, £50 or £75 and its hard not for every local at the bar to be aware of your business. and now they go for £105, god forbid, we're all going to be burnt at the stake!