While I was self-employed (as a partner in a very long established firm) for some time, I stepped out five years ago and never looked back. I was lucky because I was given the blessing (and freedom from restriction) to compete against the old firm in the same work, and because of that took little time to re-establish in the new role on my own.
That put me in a relatively safe situation. What you are contemplating Blair is establishing a new business, and with that come a lot of uncertainty. It is a risk, but with risk comes reward too, so it is a decision worth considering.
I agree with Swink's suggestion about surveying some potential clients - I did exactly that before making the step, and while not all immediately came over, now everyone I spoke to are with me. It can be hard to get people to break their relationships in business, even when they are not completely happy with an existing supplier. But if you put yourself out there, I find eventually the chances come up as people have a further unsatisfactory experience with a supplier.
I have also found that potential customers will often give a new player a go for a number of reasons, some just to simply give someone a leg up. I tend to be like that with discretionary suppliers (but not the ones where I have strong friendships with suppliers).
If the opportunity came up to buy a business (which seems a common thing when payouts come), take a lot of care as so often these do not work out, I have seen this too often. Unless it's not a huge outlay, the risk seems rarely worth it.
Very tough decision, but you are a smart guy and I am sure you'll make it work whichever way you go.
