Travel and H1B VISA stamping with current I797 when new I797 is Pending with USCIS

[oct10_vancover]

My Current H1B is valid till Oct 2013.

What are the complication incase my H1b with new Is filed with USCIS pending and if i travel to canada on Oct 9th to Oct 12th with old I797 (Also planning to get VISA Stamping on Current I797 of current Employer).