[Editor's Note: With so much talk about the cloud and cloud computing -- is it good, is it bad -- we thought we'd bring in some industry experts to break it down. Marty Abbott and Michael Fisher of AKF Partners have years of experience working for and consulting with tech companies debating what has become a common question: Is it time to convert to the cloud?]

Cloud computing is the buzzword du jour. It promises to keep your data in a readily accessible swirl of loosely linked virtual servers rather than in the confines of a grid of connected computers. And that’s a great proposition for some. Software-as-a-Service (SaaS) companies in particular could use the cloud to develop and deploy their products much faster than before. But companies thinking of implementing it across the board should be wary of several limitations that could severely impact their future success.

As consultants to some of the most forward-thinking tech companies in the business, we’ve gained early insight into the risks and advantages of embracing the cloud. (One of our clients is an early adopter of a majority of Amazon’s suite of web services in this category — EC2, S3, SDB, SQS, EBS — a whole lot of acronyms for software that lets you host your application in the cloud as well as quickly store and retrieve large amounts of data from it.) So based on that experience, here are our top five concerns:

1. Security. Not a month goes by without us hearing about a security breach or leaked personal information. Which begs the question: In the cloud, where exactly is all this data being stored? Who has access to it? And how easy is it for someone who doesn’t to get it? The answers to these questions just aren’t as clear cut as they need to be for many SaaS businesses, especially those handling loads of personal data.

2. Non-portability. While some cloud computing platforms can work with industry standard software like VMware, they still differ from vendor to vendor. An example to illustrate why this is significant: Let’s say you want to store an application or website on Amazon’s EC2 cloud platform. In this case Amazon is the vendor, and you build what is called an Amazon Machine Image (AMI) -– basically the code you used to develop your creation, and any related libraries or data. Then you debug it and ensure everything works. But now that you’re done, you can only use this AMI within EC2 clouds. If you want to access or use the data you’ve stored from another platform, you have to go about recreating your AMI all over again –- probably not the time saver you were hoping for.

3. Control. When you entrust an application to the cloud, you’re basically turning control over to a third party. This third party determines whether your application runs or not, whether your site loads or not and how to respond if your application or site fails to work properly. This raises the issue of service level agreements (SLAs), documents that outline the service a cloud platform provider agrees to give its users. Many platform providers don’t guarantee anything. Amazon offers 99.99 percent availability only on its S3 storage service. If the major advantage of cloud computing is greater availability, more companies offering clouds should guarantee uptime, as well as remuneration for clients when problems prevent their applications or sites from working properly.

4. Limitations. Even though cloud vendors are actively whittling away at the limitations of their platforms, businesses should always ask about limitations before committing, as they can lead to serious problems if not considered. Here are some things to take a close look at:

Persistent storage on virtual servers. Make sure when a cloud server reboots, the information