Well I got the eminence basslite s2010 for my Rumble 40...
I tested with a passive Musicmaster bass. The pickup is on par (output wise) with my passive fender p bass.
The results are exactly what I expected.
The reason I upgraded the speaker was to see if the Rumble 40 could be more than a home practice amp, and be sufficient for live use with my vintage rock and soul pub trio... We have acoustic drums so it can get loud sometimes.
I found the original speaker lacking. When the volume reached about 7 the distortion was noticable and if cranked up to 10 it became slushy and unusable. Over all it was not loud enough to work for even the quieter live gigs.
So I installed the eminence basslite s2010 and found to my delight I was able to crank the volume all the way to 10 without the speaker breaking up. The tone is better and cleaner over all and if you like the tone of the original, it's safe to say you will like the tone with the s2010. It's more or less the same sound, just louder.
I didn't feel the need to change ports or install padding inside.
Over all results? I would say it's very capable of handling a small room gig. I have a Rumble 800 with the power switch. I often put the switch on the quieter setting and turn it up to 8-10 on the master volume. This works great for pretty much every indoor venue. Outside on large stages I put it on full power and let it rip.
Can't recommend the 800 (not digital one) more highly. Best amp ever.
Comparatively, the 40 is about the same volume as the 800 on the lower setting. The 40 does lack noticably in low end. The single 10 is no match to the 2-10's...
The good thing is the 40 has a DI so it can be put in the PA to get that little bit extra needed umph.