For through-cuts this should never become an issue if one thinks ahead and sets the table/blade height correctly for the thickness of the stock you are working with. If you are working with different thicknesses, adjust for the maximum thickness. Yes, it can be argued that if you are working with radically different thicknesses it is a safety issue to have too much blade exposed above the thinner piece. But if you use the upper saw guard and your saw is aligned, I don't think this is a problem.
Even for dados and grooves, where you may want to fine-tune or sneak up on the depth, this need not be a problem in most cases if you plan ahead. Most dado cuts that would require the the use of a floating or extension tables to stablilize the work piece involve cutting sheet goods where you won't need to make a dado that's more than 1/2 an inch deep and usually less. You can make these cuts in a single pass. Before setting up your extension and floating tables, fine tune the depth of the dado with a piece of scrap that's small enough that you don't need all those extensions. Once you are dialed in, then add your extension/floating tables as needed and make the cut in the real work piece in a single pass.
On the few occasions where I have needed to make a really deep dado/grooves in solid stock that I didn't feel comfortable doing in a single pass (like for my patio door project), it has been in the edge of my work pieces and I have not needed to use extensions or floating tables at all (although I did use my outfeed table which adjusts automatically to the table height using Dusty's outfeed table design), so table height adjustment wasn't an inconvenience.
If you are doing the kind of work where you need to cut very deep dados/grooves in multiple passes in wide timbers that need the extra support of the extension/floating tables, you can probably do it on your Mark V, but then you will indeed have to deal with the hassles of setting up and breaking down of the support tables between passes. For most of us, I suspect that is a rarity. If you are routinely doing that kind of work, you probably already own or should own a stand alone table saw.
Well, that was a long post without a single original thought. Sorry.
