I initially tried the Swamp Thang in a Vox AC15 which perhaps sounds a little insane baring in mind this is a dark, super-efficient 150 watt monolith voiced more toward the west of the Atlantic - as someone who loves to experiment however I thought it was worth a go.
If anyone ever questions what difference a speaker can make to a rig, this is certainly the speaker to show them. Volume-wise the AC-15 was pushed further toward it's larger brother and you could audibly hear how much low end was freed up. The bass frequencies were more like something you'd hear from a 4x12 than a small combo, where as the top end sounded a lot more restrained and less spikey than what came stock in the amp. The clarity was enhanced however, so were the limitations of the amplifier. It took the AC-15 from a fantastic rhythm players amp with a charming early break-up to something loud, but a little flat and joyless.
The real joy came however, when I put the stock speaker back in the combo and ran the Swamp Thang in a separate 1x12. The rig came alive as the flat top end was enhanced by the stock speaker however you got the deep, rich bottom end and clarity of the Swamp. The varying efficiency didn't seem to matter as the combo was stacked on top of the 1x12 so the combo was closer to ear level. It's definitely worth experimenting with if you can.