Here's what I have so far by way of impressions.
Things to keep in mind - I don't use midi or spdif/adat thru BFP so the lack of these things on the Arrow doesn't factor into my thoughts really.
The two primary benefits of the Arrow (given the current state of things):
- single thunderbolt 3 cable for data and power
- UAD plugins are pretty nice and I do find the idea of tracking with unison preamps interesting - this feels like a "bonus" since I don't really do this with the BFP. Yes, they are expensive, yes the unit is a big dongle, but you don't have to use them and I don't intend to step into a massive library of UAD plugins. But having a couple at hand is nice.
edit: Obviously the big third one is the potential elimination of the current glitching issues
Points for the BFP (in my opinion - but especially pleasing to me given the age of the unit):
- better tolerances - buttons, dials, etc.
- louder and clearer headphone amp (I don't listen to a lot of outboard monitors due to environment so headphones are important)
- better latency (decent amount - something like 7ms roundtrip vs 12 at 48khz and 128 buffer) - this surprised me given Thunderbolt 3 but RME's reputation in this area is rock solid.
Some things I've noticed that I'm unsure about:
- Arrow "clicks" a lot as it powers up - turning on, waking from sleep, switching settings - it's audible and slightly annoying and it takes a couple seconds for the machine to come online
- BFP has option for 1/8 or 1/4 inch headphone jack which is super convenient at times. I think I might miss that on the Arrow.
- Totalmix is complex and often overkill for my needs but offers more power and flexibility and lower overhead from what I can tell (this is not scientific) - I don't need all that routing but I'm not convinced UAD's console is as efficient regardless
- I did a quick test and the BFP does work well with the iPad Pro. Obviously Arrow doesn't do this. Nice to have, not need to have.
To sum up: I'm not sold on the Arrow and I might return it yet hoping for Apple to resolve the USB issues. I think the BFP is a great unit and since I'm not super interested in the UAD plugin ecosystem I'd rather keep using it but the current audio issues are giving me pause.
Hope that helps.