you can't say that you only loose features with ms codec! ms codec is the most unusable codec i've seen, primary because of worst picture quality. these cards that are using ms codec are usually just a generic texas instruments fw controllers and ti chip is not dedicated for video.
similar to this, the reason for pinnacle and matrox why they don't support realtime dv, is their chipset. they use very old chipset (c-cube) that is not designed for dv. this chipset is not capable of realtime dv editing.
this can be a very big problem not with transitions, but with filtering. if you apply filters, you will apply them on the whole clip. sometimes, there are three filters, or even more, needed to be applied at the same time. if you have to wait for rendering, you wait all night.
i tried to find those pinnacle cards that you were talking about, with no success. i suppose that they are hardware codec daughterboards, with sony dvbk-1 codec. few years ago this codec was only in the very expensive editing boards and systems.
now, the conclusion: if you need features, buy a cheapest firewire card and load your computer with a various software, effect packages, titlers, plugins etc. if you want picture quality, then go buy yourself more expensive dv editing card that will come with good codec, and if you have a lot of work, be sure it is realtime. (realtime means realtime, not realtime in some segments). after a few days of medium serious work, you'll see that you can't sell fancy effects, but you can make a nice money if your picture quality is good and if you can use quality filters.
if you take a look at the market, and if you exclude simple firewire cards, and if you don't go over $3k, you'll find pinnacle, matrox, dps and canopus.
dps is mjpeg, it is not good.
matrox and pinnacle can apply two filters with their strongest cards.
i suggest, if somebody wants to edit dv format, to take a closder look at the canopus, and load the computer with fancy plugins. that must work.