Well, I can not help you with the comparison that you asked about, as I have not heard the Airtight, although I have heard good things about if from a friend of a friend, (not that that helps you any!)
However, I have recently bought an used Dynavector XV-1S from a friend, and I must say I am impressed. This is my fifth cartridge in as many years, and it is by far the best I have owned.
My first was a Benz Micro Glider II, (bought new for $800, which included installation by my dealer), which was competent, but somewhat uninvolving after awhile. (It sounded too much like listening to a CD, which is decidedly NOT what I wanted.)
My next two cartridges were both Koetsu cartridges. First came the "Black", (bought for $1,500 new, again installed by my dealer), a very nice cartridge, with a great mid-range (very lush, but great on vocals), but with a slightly restricted treble, and a pretty loose bass response. The Rosewood Signature (bought for $1,200 used off Ebay), I replaced it with was much better, as the treble was pretty well extended, and the bass, while still a bit loose, was also deeper. The one thing I really liked about the Koetsu cartridges, was how deep and dark the backgrounds were, compared to the Glider. (However, I eventually craved a cartridge that had a deep, tight bass response, so I knew I would be giving up on the Koetsu line.)
My fourth cartridge was a Shelter 90X, (which I bought for $1,250 on Audiogon). This was a near great cartridge, as it had great bass response (the deepest I have heard, I think), and a very well extended treble response.
However, unlike the Koetsu cartridge, the Shelter did not have nearly the deep, dark backgrounds, that I had grown to love. Still, I lived with the cartridge for about two years, and for the money, it was well worth the price of admission. However, I eventually I knew that I wanted that deep, dark background once again.
A few months ago, my friend bought a Brinkmann Balance, including the tonearm, and the EMT cartridge - and, Yeah, I know, and he knows, that he's a lucky bastard! :-)
Therefore, he asked if I wanted to buy his XV-1s for $1,900. I said sure, as I had heard it in his system enough to know just how good it was. I knew it had pretty good bass response, as well as a very low noise floor. When I got it all dialed into my system, I was very pleasantly surprised by how deep and tight the bass was (within spitting distance of the 90X's bass extension, and I think a bit tighter actually), and the treble actually seemed a bit more refined. The mid-range, while not as warm, seems more refined and detailed than the Shelter or even the Koetsu cartridges were (which really surprises me actually, as I loved my Koetsu mid-range!). However, the really big surprise was how it soundstaged and imaged. I have never heard my speakers completely disappear on virtually every recording before. (They used to disappear on my better recordings, but now, it seems on most recordings, that they just are not there. I think this cartridge has taken my system to another level.) I think I have found the cartridge I will be living with for a very long time.
My recommendation is to give the XV-1S a try, as I doubt you will be disappointed.
My two cents worth.
