Security analysts have scanned hundreds of "CD Reef V4 Portable" executables available on public torrent trackers. The results are alarming:
BurnAware is perhaps the best direct replacement for CD Reef V4. They offer a "Portable" ZIP download on their official site (no installation required).
If you are strictly anti-proprietary software, InfraRecorder is open source and available via PortableApps.com. It is very basic but 100% reliable and safe.