There are many species in Honduras not covered by the Costa Rican guide (if dividing Central America into zoogeographic regions, Honduras and Costa Rica are in different regions and there are some clear differences in avifauna). So, no doubts the Howell & Webb guide is a must-have for any birder visiting Honduras. BTW, Luke (aka "delougl"), you might want to take a look at Tom Jenner's page. It provides much useful info on both Guatemala & Honduras:
http://mayanbirding.com/
I wonder why are Honduras and Costa Rica in different zoogeographic regions.As I lived in China,in my impression the two countries are in tropical areas and they both should belong to Neotropical Region.But what are the difference?