After March 2013, when the last phase of the AIA will enter into force, there will - for reasons of vesting a date of invention - not be a difference between filing a US provisional application and filing a priority application in any other jurisdiction.
The disadvantage of a US provisional is that it is only a place holder, for which you have to pay more than $100 to achieve just that. If you file in other jurisdictions you have several options:
1) not paying fees, which in many cases will still give you a filing date and filing number of your application and which thus allows you to use the application as a priority application for a later PCT and/or US application.
2) pay a filing fee + a search fee. With this option, which is available in some jurisdictions, you will get within the priority year a novelty search + a (preliminary) opinion on the patentability of your claims. This can thus help to decide whether or not it is worthwhile to continue the patenting process, or whether or not you have to adapt your application.
In some countries (where a so called patent registration system is available) you will also automatically get the patent, which you can enforce in a court.
Hence, filing a US provisional may be an option, but you should also explore other options which are available to you and which even cost less, or which provide more information.