PayPal is a very good company considering how fast payments can be send around the world ...
what PayPal should do though is cooperate with registrars to confirm whether a transfer/push has actually taken place ...
or registrars should create a Uniform Transfer/Push Confirmation system , eg. an email send by the registrar to a company (eg. to PayPal) after a request from the seller or a webpage on the registrar's site with a confirmation of the transfer/push ...
moreover , transfer/pushes (and confirmations) should be standarized so that banks will accept them as proof (similar to proof of receipt for tangible items) and cancel/void the chargeback ...
if you are really worried about chargebacks on PayPal , you can ask the buyer to use
PayPal Mass Pay (supposing that the buyer trusts you since he was prepared to send a classic PayPal payment in the first place)
funds should be transferred to the PayPal balance before a payment is sent out and CCs are not accepted as a method of payment ... thereore a chargeback is not possible ... it is also very cheap , 2% of transaction paid by the buyer (capped at $1)
a negative side is that currently PayPal does not accept bank transfers to PayPal balance in many countries (and having enough money in PayPal balance or getting funds in PayPal balance from a friend is not very common/easy , especially for non-domainer buyers)
sashas - since you are probably transferring funds to your PayPal account so as to make a Mass Pay payment make sure that the seller/receiver-of-funds is legit and can be trusted ... also check out whether the domains are stolen or whether his forum/email account has been hacked (and therefore whether the person you are negotiating with is a scammer)