EL-34 vs 300B based integrated amps

I've heard el-34 called the "poor man's 300B". Well, I'm running a Cary SLI-80 in triode mode with EL-34's and it sounds lovely. What kind of increment in sound quality could I expect by moving to an SET integrated, such as Cary 300-SEI or one of the ASL 845 or 300B SET's, Sophia, others...

My speakers are Silverline Sonatina II's 93db 8 ohm - I think 10 or 15 watts would cut it, am I dreaming?

I have an ASL Orchid 2A3 integrated (3.5W/ch) into Coincident Triumph (94 dB, 8 Ohms) in the bedroom system. It sounds lovely at about 80-85dB in a 16x25 room. Obviously not much deep bass but the mid-range is very transparent and upper end is very liquid and clear. Vocal and small band Jazz sound great.

So the three main issues are
1) type of music
2) volumne level desired
3) Room size

If you do go with SET, adding a powered sub can help very much. You will need a tape-out loop into a cross-over to filter out bass from the amp. Send the bass to the sub. So the SET only amplify from 80 Hz and up. You can also try it through speaker level as well, but I think line-level would have better results.
I've heard Alan Yun's Silverline Sonata III speakers with a 7 watt SET amp. Wonderful. I own LaFolia's and am playing with a VAC 70/70 mk III. Superb. Alan's speakers are very senstive and respond very well to low wattage amps. Go for it.
I use a REL Strata II in conjunction with SET 300b amps with the speaker level inputs; works simply great.