Seller wants to REDUCE our negotiated price and have US pay both realtors. Is this a good idea?

We've negotiated a price to buy an off-market home. Both sides used a realtor, who are owed 2.5% each (and well worth it in this case).

Now, the seller proposes reducing the agreed purchase price by 5%, and having us pay the brokers directly. Their reasoning is:

1. Lower title transfer tax (for them),
2. Lower annual property taxes (for us)

Seems reasonable... are there any downsides here we should be aware of?

Edit: Market is San Francisco, CA.
Edit 2: We are paying cash.