Hi
@sriramkb !
This is one of the most asked questions regarding Family Class Sponsorship Inside Canada.
The short answer is: yes, your wife is allowed to leave Canada anytime and if she has a valid visa to get back to Canada, she would be ok to be admitted at the border. The thing is, if for whatever reason she is denied to enter Canada at the border, your app probably will be rejected, because if you apply inland, you must remain in the territory.
Some people take the risk and travel, some of them are successful and others don't. If you run a quick research here you will find lots of stories and examples, but the truth is that no one can guarantee that its gonna work. It's up to you take the risk and be aware that final decision belongs to the CBSA agent at the border.
Also note that an OWP its not a travel document, it gives you the right to work while you're waiting final decision and give you temporary status in Canada, but I'm not sure if it would make any difference at the border.
Whichever choice you make, good luck and keep updating,
André