I talked to Paypal today to make sure I wouldn't have a problem if I sent gift payments to my wife a couple times a week, this is what they said:
If both accounts are BUSINESS accounts then eventually the system will catch on and limit or shut down accounts. Businesses don't give other businesses money, so if it is happening too much they know it is just circumventing fees.
As long as one of the accounts is a personal account there will be no problems.
I imagine most of us have business paypal accounts even though we treat them more as personal ones. Any way you go, just don't do Business to Business gifts.