I would give them 2 weeks as agreed, but be prepared to walk when you finish the conversation. I know you feel loyal and hard to replace, but the fact is you can and will be replaced. The fact that you are leaving means you are unhappy, underpaid, or whatever...and your employer will want you out of there.
That says it in a nutshell.
BTW notice is a courtesy, not a right. Some employers "think" they are entitled to it but won't give same. Avoid them. I wonder how many of those that say give the notice are current or former busness owners.
