"Cloud" Security Applications: Warnings...!

There is a growing business in "Cloud-Based" Anti-Virus and security applications.  (e.g. Panda Cloud)  Are they any good?  

Reviewers mostly say that they are.  However, all the reviews I've read so far are based on the same type of useless methodologies as most "big-name" security applications.  (For more explanation on why these testing standards are useless, see my post:  "What's the best Anti-Virus?")

My quick answer:

At this time, I believe that Cloud-Based Anti-Virus and security applications have significant weaknesses and vulnerabilities.  I definitely would NOT use one now, nor in the immediate future.  

Why: 

One of the main "benefits" touted for Cloud AV's is that the virus signature database is not stored on your PC.  Instead, it's stored on The Cloud, where it is "updated more frequently" than it would be on your PC.  Counterpoints:

1. The frequency of the signature database updates -- in this kind of situation -- will provide little or no "real world" improvement on the security of your PC.  In fact, it benefits the "Cloud Provider" a lot more than it does you.
2. For a security application to be effective, it must be able to work faster than the virus itself can work.  If the signature database resides in the cloud, even under optimum conditions, accessing the Cloud signature database will be far slower than if it resided on your PC.  Delays in accessing the signature database can have dangerous repercussions.
3. It is very normal for access to the Internet to be unreliable and unusually slow.
4. If you have no access to the Internet, your security is severely impaired or non-existent.  ...Even the publishers of these applications admit this.

Another so-called benefit of Cloud-Based Security is that it requires less "System Resources" than applications installed on your PC.  Counterpoint:

1. For some older Windows XP systems, this might be useful.  However, any system that is well-maintained and "Vista Compatible"-- or currently running Vista or Windows 7 -- has more than enough computing "horse-power" to provide better security using a security application installed completely on your PC.