I prefer to record directly to the hard drive as opposed to the card. It is faster and less likely of card write error from RF transmissions
Wrong. RF Immunity is tested when applying for CE and FCC certification. So unless you use a homebrew recorder, thats not an issue.
In fact, the probability of a harddisc failure is higher than a card error, because the HDD is a mechanical system with lots of moving parts. I already had a defective HDD, the only defective flash USB memory I ever saw was obviously a fake and could be detected with a test program before any real data was written. Unless you buy from obscure sources, the memory card is the better solution: reliability, power consumption, access times and robustness all speak for memory cards.
My motto for HDDs: backup, backup, backup. And avoid mechanical shock... thats hard to do for a portable recording system.
BTW a flash card as OS drive for a computer is muuuch faster than a HDD: my workstation at work has a SSD as boot drive
and a HDD for data that is mirrored by our company server to avoid data loss, so I know from own experience how fast that machine boots compared to my old HDD-only workstation.
If given the option, I would replace a HDD with a flash based memory in an audio recorder without thinking twice - the advantages (and my experience with Flash based embedded systems from an engineers viewpoint) far outweigh the risks.
Greetings,
Rainer