Portability
Portability TO OpenBSD

Most applications are trivially portable to OpenBSD
Problems are generally around buggy/insecure behaviour that is causes the application to crash instead misbehaving silently.
Threaded can also be a problem.
"Bloatware" may be more difficult
OpenOffice, Mozilla were painful to port
Mostly because they are a bugridden mess
Depends on existing environment
*BSD applications are generally simplest
Linux developers tend to use non-portable GNUisms