I reckon the voice activation will be the feature that filters out most recorders we're used to.
You did your research already, Olympus LS-5/10/11 will fit the bill.
You might also take a look at Yamaha Pocketrak C24/W24 (sold as Sanyo ICR on certain overseas markets).
Sony ICD series will either fail on the SD card requirement, or the uncompressed WAV. The ICD-MX20 takes memory sticks, but records to lossy formats. The SX7xx/9xx series does WAV but lacks the card slot.
I guess the Olympus models are the ones that most here will vouch for. IIRC, the line in has a hardcoded bass roll-off, but that's no concern for your usage.
LS-10 is discontinued, LS-5 is branded for the EU market and not really available in the US, so LS-11 will probably be the easiest one to pick up. With 23h battery life, that should be plenty for you. Retails for $225.