BBC presenter Jonathan Ross has joined MTV’s Multiplayer blog and Kotaku in highlighting lag issues with Project Natal.

Ross playtested Natal yesterday with his family at a special demo arranged by Microsoft, later tweeting his thoughts. “Natal on Xbox impressive,” said the UK TV and radio star. “Not quite there yet, I think, but they have until October and if they get it right… sky’s the limit.”

Ross’ son recorded part of the session, later posting it on YouTube. The video shows Ross flailing around, playing the ball game featured in last year’s E3 demo. You can watch it below.

“Not quite there yet” would seem to be a reference to Natal’s lag. There’s a note in the video saying that the Ross family were told by Microsoft that response times would be “nearly instant” by launch, but it’s clearly an issue.

The extent of the problem has been quantified by the MTV’s Multiplayer blog. In an article published yesterday, Russ Frushtick measured the lag precisely, during a prolonged session with the device.

“I had a pretty large sample size,” said Frushtick, “sitting through 5 demos, capturing about 40 different movements from a variety of journalists. Across those 40 movements, the fastest life-to-screen transition was .08 seconds, while the slowest was .12 seconds. A tenth of a second was the consistent average, though.”

“What that means is that, in its current state, Natal is not instant, one-to-one motion capture,” said Frushtick. Though he notes, “Even high-end Hollywood studio motion capture devices have a slight delay, and a camera sitting in front of your TV doesn’t come close to the fidelity of 30 cameras in a massive studio.”

Meanwhile Kotaku’s Brian Crecente has pitched in on the issue too, employing the term “uncanny disconnect” to describe the lag. The opinion piece isn’t as forgiving as MTV’s, suggesting that it could even lead to the failure of the entire concept.

“I realized, as I played around with the Project Natal prototype… that I was spending more time examining the game’s reaction to my motions than I was having fun,” said Crecente. “Until motion control is perfected, I realized, the pursuit to make it more precise in video games will result in titles that are less fun to play, not more.”

He continued, “The biggest risk motion control faces is that the paradoxical nature of that uncanny disconnect may lead gamers and developers to believe that the basic concept is flawed. In other words, if game developers get it wrong enough, people won’t want it anymore, no matter how good it eventually gets.”

Last year, Traveller’s Tales boss Jon Burton revealed his concerns over Natal lag. He suggested that it will greatly reduce the types of games that can be developed for the platform.

Microsoft have until December to resolve the remaining issues. Despite Ross’ suggestion that Natal would launch in October, the official word is that Microsoft are currently sticking with a Christmas release.