Summary: A deal is only as good as its best alternative. Keep improving your alternatives until you have a signed term sheet. And keep developing your current offers or they will die. Finally, don’t say "shopping around", it puts investors off their stroke.
My understanding is, shop around, but, don't say it as "shop around". Use other languages or excuses.
http://venturehacks.com/articles/shop-around
This is the summary:
Summary: A deal is only as good as its best alternative. Keep improving your alternatives until you have a signed term sheet. And keep developing your current offers or they will die. Finally, don’t say "shopping around", it puts investors off their stroke.