Unsure what is it that you are exactly looking from online reviews or impression outside of head-fi thread, but there is enough discussion here with some in depth disassembly and mods. I understand your predicament since a little known company is asking 1k USD price for a headphone amp. But having heard so many amps at so many different events, meetups etc plus owning a slew of Schiit amps, I can safely say even with stock LME49720, it's the best sounding amp I've heard till date.
Recently I got to hear Cayin iHA6 which is a well received amp by many online reviewers. Hear them side by side, you will realise the contrast and how much you are left wanting from iHA-6.
In another comparison a friend of mine made RJM Sapphire V4.00 for an owner of Eddie Current Black Widow since Sapphire sounds really good. But H20 puts Sapphire to shame even with 49720 in terms of tonality, extension, speed and details. Of course your own listening habits, the headphones and lastly your DAC do play an important role in such comparisons. These comparisons I speak where done using HD 800/S, LCD-X, K712 Pro using either Holo Spring or SMSL M8A (modded with 49720 at I-V and LPF stages instead of OPA1612)
As for SE input, yes it does phase splitting for balanced outputs, so you are covered there. I mentioned this in one of my previous posts actually.