: but one is hard chined the other has a round bottom. What are the advantages
: and disadvantages of each?

Another can of worms! There is a design forum on this site, but I think you'll find more discussion in the building forum on the merits of various designs. If you can get your hands on a copy of volume 113 of Woodenboat, Chris Kulczycki gives a good discussion of the merits of various designs. If not, let me know, I can fax you the article or email the text.

In the archives try searching "design" or "Greenland."

The hard chined S&G designs are probably easier to build and have come out right than multi-chined boats. You may want to read the trail of tears in George McQuade's journal concerning building Nick Schade's multi-chined S&G Guillemot. The second link is to Nick's journal. Even Nick, who is an experienced builder admits to problems.
http://www.cyberbeach.net/~gmcquade/Kjournal.html
http://www.guillemot-kayaks.com/Building/Stitch&Glue/S&GJournal.html

I think I'd go with the simpler design for a first boat. A lot of folks have reported good luck with Eric Schade's Merganser design, check it out at:
http://www.shearwater-boats.com/

Some other links you may want to look at are:
http://www.guillemot-kayaks.com/Design/StabilityArticle.html
http://www.guillemot-kayaks.com/Building/Building.html
http://www.guillemot-kayaks.com/Links.html

Good luck!