Currently, there are too many points of failure in the srcpac script. (Just grep exit 1 in the source...)

It would be nice if srcpac was capable of (almost) unattended system updates. For instance, srcpac -Syub should never fail before at least attempting to build all the packages. Building usually takes much longer than pacman updates, so the srcpac script should be much more robust than pacman itself. (This is currently not the case.)

Presumably, installing only packages that build properly and ommiting other updates could cause some programs and libraries to malfunction. But a failed build does *not* mean that srcpac has to stop. A few suggestions:

0) It would be great if ugly tricks like (yes | srcpac --noconfirm -Syub) were not needed. Builds take long and the user just can't watch them all the time. pacman doesn't ask you to confirm every single package update and neither should srcpac.
1) In the worst case, srcpac could have a fallback option, such as installing the failing packages with pacman. (Anyway, when an ABS entry does not work, it is not obvious where the corresponding binary package came from and what it actually contains...)
2) If srcpac fails to build a package on which nothing else depends, it should just report this problem and go on, rather than failing. (A package that does not build should not get into the ABS tree, but it does happen quite often...)