I tried this out last weekend based, largely, on Mr. Tips' youtube vid and definitely buy that, with sufficient practice, you can gybe relatively quickly. The things that can really slow you down is the slimmer margin through which you inside gybe the kite and subsequent higher likelihood for getting a wrap. That, and the fact that you do completely collapse the chute when you gybe it, but if done reasonably quickly the boat shouldn't really lose too much momentum.The 30 seconds longer to gybe an asymmetric on was a guestimate (I've never actually timed it) with a full racing crew based on 10 seconds longer to ease pole to forestay and remove, 10 seconds longer for the gybe itself, and 10 seconds longer to attach pole on the new side and square back. It may take longer on some boats, or if the crew aren't practiced, and will definitely take longer with less than a full racing crew (e.g. double-handed).
With a full racing crew the bow person disconnected the pole while the mast person lowered the pole tip to the deck. During the gybe the bow person ran the clew back to the spreaders and pulled down to pop the head through. They then ran back to the bow to re-connect the pole on the new side while the mast person completed the dip-pole maneuver and re-leveled the pole. The cockpit crew operated the tack line and guys.
One of the reasons it takes longer than a symmetric gybe is because the steps are sequential, rather than concurrent, but this also makes it plausible to execute short-handed, which is difficult or impossible with a symmetric kite due to the numerous concurrent activities involved.
That said, an end-to-end gybe on an S-kite by a well-drilled crew is inarguably faster.