Can Second Life be a useful training tool?

Linden Labs (the creators of Second Life)claim the following:

"The Second Life Grid enables students, educators, and businesses to create innovative environments for distance learning, computer-supported cooperative work, simulation, new media studies, and corporate training.

The Second Life Grid provides an opportunity to use simulation in a safe environment to enhance experiential learning, allowing individuals to practice skills, try new ideas, and learn from their mistakes. The ability to prepare for similar real-world experiences by using the Second Life Grid's tools for simulation has unlimited potential.

Students and educators can work together on the Second Life Grid from anywhere in the world as part of a globally networked virtual classroom environment. Using the Second Life Grid as a supplement to traditional classroom environments also provides new opportunities for enriching an existing curriculum."

However, I was recently involved in a training seminar about/in the world of Second Life (SL) and I have the following concerns:

Speed - SL requires a high speed internet connection to function properly and even with that, it has a hard time keeping up. It often takes 3 to 5 minutes for the objects and textures in small local area to load. This means that training participants must be present well before a training session begins and said training session should remain as stationary as possible.

Realism - SL looks good if a lot of effort is put into the environment surrounding the participants, but this is a double edged sword. If you skimp on design or go overboard your trainees may fail to give learning the attention it deserves due to environmental distractions.

Simulations - SL and its controls do not allow for much beyond soft skills training. I have yet to see a good training simulation which is not world specific or requires exceptional in world skills and knowledge to be functional.