What is more preferable depends on your requirements. If task service needs to be available to other clients (not only your web application) then the best is to rely on JMS as a transport that could be part of transaction, meaning message will be sent to task service only when transaction will be committed. But if your web application is the only one that makes use of task service I would recommend to use local task service.
Regarding upgrades, we are close to release 5.4 which provides much better support in this area so I think it's worth to wait little bit more for 5.4, of course you can already give a try with beta1
HTH