I deeply respect the opinions of our veterinary care professional-members here at TCS - I am often humbled by their expertise and knowledge. A few of them have made wonderful suggestions here which, when employed in my own home, have made remarkable positive changes. However, when it comes to anesthesia preference, I am also stating the facts as they pertain to my own personal experiences.
I have lost cats due to ketamine use, confirmed by post-mortem analysis. Abbycats lost her beloved Thomas ... and I personally know 10 or more people in my own group of family/friends who have also lost cats from ketamine reaction. I do have to say that the majority of those people did not have any sort of confirmation of that other than what their vets told them, but the post-surgical symptoms those cats presented were all ... well, let's just call it 'indicative'. My dearest friend Tricia lost her sweet Toby and was told "Well, he must have had undiagnosed cardiomyopathy (which is prevalent in cats, by the way) - it wasn't the ketamine that killed him, it was the cardiomyopathy!" Ummmm, would it not make better sense then, since we know that cardiomyopathy doesn't always show up on most pre-surgical blood screens, to use an anesthesia which would be safe for ALL cats?
Please don't misunderstand me ... I am certainly not implying that gas anesthesia doesn't carry risks - it does. But IMO and for my cats, the risks of ketamine use are greater in number and severity.
It should also be noted that not all veterinary clinics use the box-induction method. My vet has used this method in the past, but prefers the mask. He just finds it easier on everyone - most importantly, the cats. But I still hold fast to my original thought on box-induction ... I would rather my cats be stressed for a few SECONDS than die from post-surgical complications of ketamine. If performed correctly, gas box induction should be almost immediate, no more than a few seconds at most. If your experiences are different, Petnurse2265, then in the sincere hopes of trying to be helpful to you, maybe a little tip I heard while in my own vet's office one day will assist in some small way ... my vet noted that in his experience, box induction seems to go a lot easier and more importantly, faster for the cat if you place a ~warmed~ blanket or other such material in the bottom of the box before inserting the cat - they don't resist as much and so the process goes quicker. I don't know if this will change your experiences, but it is offered in the spirit of trying to help.