I would offer my opinion, having been in the same situation. I have an original Foreplay (all the mods), a multi switched fully modded Quickie, and a just breaking in Crack Preamp; all in use with a Submissive attenuator before my amp. I've done the A,B,C comparison; bought better cable and repeated, switched out speakers and repeated. I would say that it all depends on the completeness (synergy, I know, I hate those audio "zero meaning" descriptions too) of your system. I use horn speakers that are pretty efficient. To match the best sound I've had to just sit and listen. My digital source sounds best with no pre, just source, dac, submissive and amp. Vinyl has needed the extra grunt of the Crack Pre so it is Table - Seduction- Crack P- Submissive (I listen to everything - blues to funk to classical to show tunes). My Quickie sounds best before my super tweeters, nice and clean. It's a bit of a bother having all these big azz boxes on my shelf but I'm on the way to consolidating some of these builds.
I would say that a basic Crack Pre beats out a modded Foreplay, I, II, or III (in my opinion). The comparison of Quickie to Crack Pre is pretty cheap to try and if you don't like it you can go back to using the Crack as a headphone amp or make a Quickie headphone amp.
I do know that you should have a Submissive, period. Just mod it for more inputs as needed. It's beat out all of the other attenuators in the volume range I listen.
I don't know about the upcoming Bottlehead offerings, my beer budget determines my incremental upgrades and I have too much ADHDOCD to wait on some of the delivery times but if you can swing it the BeePre may be the upgrade you are searching for, it is the top of the line for a reason.
Alonzo
Gameroom:>Mainline to HD820, SR45 to Pipette
>BeePree Kaiju & SII to Altec 19 knockoffs
Office:>BH Stat amp to Koss 95x, T20 SET to JBL 4309s
Den:> MorePlay 845 SET to Altec Valencia's