I am currently only compiling for OS4, but then again I only really started doing much coding since having my A-One and OS4.
I did once write some stuff for OS3 in HiSoft BASIC but that is unlikely ever to be finished as HiSoft BASIC and anything written with it refuses to run on OS4.
All my coding has been invoilved with converting OS3 software to OS4, to either fix problems or add features missing in the older versions. So OS3 versions do exist already, just older ones.
I personally think it is time to move on and leave OS3 for dead and concentrate on the future of the Amiga OS rather than compile for every variant and emulation of the OS that exists.
So my main concentration is OS4 only. IF it is possible and not too much effort I may compile for OS3 but not having any OS3 nor Morphos machines to test such a compile on I would not guarantee it working nor be able to give support to any cross compiles. Someone else said similar earlier about the importance of actually having the machines to test your stuff. My A1200 gave up long ago and had not been switched on for ages since OS4 was available on my A One.
Also when porting OS3 to OS4 one thing you can do is remove many of the limitations that the older versions had due to using old hardware and a less featured OS, so why look back
Some work in progress screenshots of my OS4 project can be seen at
http://www.eavesweb.plus.com/testpageAnyone wanting to run DU on 68k can always get version 1.03 which has been available for a long time at
http://www.syz.com but don't expect that version to perform anything like the PPC native 1.5 version. That is an old version for old hardware and thus written in a limited way appropriate for the times. Likewise the PPC version expects an 800MHz G4 or similar as base level and 16 or 32 bit screenmodes only. An OS3 compile would probably be a waste of effort for little gain.
Let's look to the future not the past.
Bill.