As you're already aware, the LFM-1 and LFM-2 are siblings of the STF-3 and STF-1; Dr. Hsu was on the design team, but the Outlaws also contributed to both subs. There are some differences beyond the purely aesthetic (the LFM's downfiring ports being one, but the LFM-1 also uses a different amp than the STF-3 and the LFM-2 is tuned lower than the STF-1). At least in general terms, the differences between LFM-1 and STF-2 would be comparable to the differences between the STF-3 and STF-2, while the lower-tuned LFM-2 may be closer to the STF-2 than the STF-1 is. That's all just estimation, though - like you, I'd be curious to hear from anybody who has had both Outlaw and HSU subs in the same setup.