mmp, i'm sorry, i completely forgot to answer your question about the soil block maker.
i really liked it and will be using it again, as a matter of fact, a friend of mine is thinking of purchasing the tiny inserts maker and the larger block maker and then we can share what we have to make different sizes.
they held up really well and i mostly poured water into the trays so they could absorb it. i think some people put them in a container with holes so it can drain and set that in a tray w/o holes but i really didn't have any problems with it retaining too much, possibly because they were in the green house and the water evaporated quickly. i did water the tops occasionally and there's a comment on that post from someone at pottingblocks.com that said:
Actually bottom watering and top watering are effective. I prefer to use Fogg-it Misters and increase the gpm as the seedlings get older. The top watering strengthens the stems of the plants and they love mist and fog.
Bottom watering is for the busy gardener. Fill the pan up with about an inch of water once a day, or depending on the weather. They are actually blocks, not cells. If you want to make a homemade soil cell maker check out http://www.pottingblocks.com/
that website has a lot of great information on it. i highly recommend them, i truly think they are worth the initial cost!