We have raised our prices gradually, in line with reasonable customer expectations and therefore customers understand and keep with you. Our reputation undamaged as a realistic increase is always fine.
An example of where it doesn't work is Intuit unfortunately, who have just added 71% to my bill, claiming to add useful feature - none of which I will ever use. In this situation the customer has lost trust in the supplier for such an huge increase, but being tied into QuickBooks there's not much I can do about it without major upheaval. But lets be clear - I really don't trust Intuit now and won't recommend them to any of my customers - who often ask what to use.
So the (im)moral of that story is: treat customers fairly and you keep their trust, but if you can tie your customers in then you can do whatever you like to them and increase your prices at will, but lose their trust.
Hope that's clear enough?
