The bees will regress as michael has said. The only way to accomplish regressing from scratch with foundationless is to cull combs and to do it at appropriate times of year. Earliest in the spring is best time for small cell building since the bees are focused very much on brooding. Leave the brood nest alone until its warm enough to open the hive. Then take you worst and largest combs and move them to the back of the brood nest so bees can emerge and replace them with empty topbars placed between you best existing combs in the center of the brood nest. It takes some time, but you can do it.
Its not a bad idea to keep both langs and tbhs around. Although I have no longer have langstroths it is not intentional. I simply decided to get back into beekeeper with tbhs this time. ALl my money goes to lumber for those. I wouldn't mind having some langstroth equipment I just happen to really like my TBHs and would prefer making more of those than langstroths. The off chance you need to have some lang equipment laying around really does make having them a good idea. If you need to share resources with other beekeepers and they aren't using similar equipment as you, then you pretty much can count it out.
Scot Mc Pherson<br />McPherson Family Honey Farms<br />Davenport, IA<br />BeeWiki: <a href=\"http://beewiki.linuxfromscratch.org\" target=\"_blank\">http://beewiki.linuxfromscratch.org</a> <br /><br />Pics:<br /> <a href=\"http://linuxfromscratch.org/~scot/pics/bees/\" target=\"_blank\">http://linuxfromscratch.org/~scot/pics/bees/</a>