yeah the LF band on the REQ is one of the least used. Sontec is tighter & preferred over the REQ but more often than not the API 5500
does most of my LF cuts & boosts it's just tighter.
I still think the LF on the REQ is useful for some jobs where you need to smooth the bottom or make things warmer/larger. All 5 EQ's I have in here have their strengths & weaknesses. The REQ has great low mids, upper mids & highs, the LF sat is useful for some jobs. The LF & HPF sections don't get used all that often. Not a big deal when you have a 5500 or a BAX.
As mentioned though I think the Lundahl output transformers help with the transient softening you're hearing Ben. I believe Tim's output stage softens things a little where the Lundahls sound more focused, bigger, tighter.