Leave US while H1B transfer pending, Canadian citizen

[potana]

I currently work for Company A, and received an offer from Company B. While Company B works on transferring my H1B, can I quit Company A and leave the country without losing the transfer? I plan to return and work for Company B after the transfer completes but would like to take some time off between the two jobs. 

As a Canadian citizen, I can visit the US without a visa. If I quit company A and leave the country while H1B is being transferred to Company B, can I reenter as a tourist in the meantime? Or will that annul my H1B?