Few updates:
1. I'm working on bypassing the CPU compatability test, to allow all CPUs to at least attempt benchmark (older CPUs will fail most miners, but will pass the JCE benchmark)
2. I'm also working on integrating coolMiner, but I came across an issue - this miner does not support benchmarking: https://bitcointalk.org/index.php?topic=4412370.msg40911245#msg40911245
3. I'll be looking at CryptoDredge next - if they support benchmarking, and have an API I can use to read hashrate at runtime, I'll attempt at integrating it into this GUI.

Edit: Seems like CryptoDredge does not have an API yet, but they promise they will have one for their next release, so good news there.