[Disclaimer: It has been one heck of a long time since I last did a pro wedding gig, long enough ago, in fact, that taking 240 pictures in total, or 10 24-exposure rolls of 220 Kodak VPS, was "going above and beyond". Things have changed just a bit since then, but though I'd never voluntarily shoot a wedding again—I'm not temperamentally suited to the environment—I think I understand this brave new world.]
Both formats have their problems, as others have been quick to point out. A JPEG is a digital slide, in that what you record to the card has little room for correction later. When you commit to JPEG, you are saying "there will be no exposure or white balance problems with my images." And that's fine if you are working in an environment where you can be more-or-less certain of the lighting, etc., (or white balance or pleasing tonality don't particularly matter) and speed is your primary concern.
Shooting S-RAW is severely limiting your size. (Yes, there is also the fact that you're permanently committed to the de-mosaicking and resampling that the camera does. That's not only a red herring, but a pickled one as well.) In choosing S-RAW, you are effectively saying "this image will never, ever, have to be larger than 8-by (8x10 or 8x12 inches, essentially A4 with a border), and there will never be a reason to crop." You're creating a beautiful image, but at 5MP, it will start to fall apart at relatively small display print sizes, sizes that would have been considered huge in my day, but which are very much run-of-the-mill in the digital world. And you have no way to predict the importance of a picture at the moment you take it—you may be taking the very last "nice" picture ever taken of somebody at any given time. You just don't know.
Now, there are people who have the time and storage space to deal with thousands of full-sized RAW images. (And in the Nikon world, there really isn't a choice. If you've committed to the D800, you've committed to 36MP if you don't want to shoot JPEG or crop to a smaller format in camera. The D700/D3 crowd only have 12MP to begin with, so annoying extra pixels and the gigabytes they bring aren't an issue for them.) There are very good reasons for wanting to decrease the file size when you can, including the time it takes to download and back up your images (even if you have unlimited storage space available). At the same time, there are some very good reasons for maintaining larger images, including the ability to create large (a usually profitable) prints.
A good compromise is to shoot your "shot list" (the more formal portraits and groupings, the ceremony proper, and whatever detail shots are expected in the cultural context) as full-sized RAW images. There won't be a great many of these (comparatively speaking), so the extra megabytes spent here won't significantly impact the total, and you have a lot of room for large prints, album spreads/covers and so forth. The rest you can shoot as M-RAW. You don't get quite the file size savings that you do with S-RAW, but M-RAW is 10MP or so and will print acceptably at A3+ on smooth papers for relatively close viewing, and can go much larger, especially when printed on a more textured surface (like canvas). If you need a full album page or a spread, you've got it. If the picture turns out to be more important than it seemed at the time, you haven't sacrificed too much, but you've gotten a two-fer on the file size, and that's not bad (especially for online/cloud backup).
But what about the workflow? The files are going to be larger than S-RAW or JPEG, no question. Start with the fastest cards and card reader you can reasonably manage. The card reader will be cheap enough, but yes, the 800x and 1000x cards are a little more expensive than the 400x and slower ones will be. But they'll save you time every time you download images, and your time is valuable too. Managing the images once they're downloaded can be done a lot more quickly as well, at least as far as the initial cull is concerned. Lightroom is great for a lot of things, but the initial import and first-pass are not its strong suits. Take a look at Photo Mechanic. There is a free trial available, so you can make up your own mind on real-world image sets, but it is stupid fast at rendering RAW (and M-RAW and S-RAW) images and letting you apply ratings and so forth. It's probably not what you want to use to develop the images, but it's a very quick way to cut the images down to a reasonable number, something Lightroom or Aperture can more easily digest, and move them into a watched folder for import. Again, you're buying time with money, but it can be a lot of time you're buying for a relatively small amount of money (especially when you compare it against the price of most of what we photographers buy).
