Although i don't own any of them, i have been seriously considering an SE synth for the last couple of months myself.
For my poly analog needs i own an Andromeda A6. I also now own a Moog Little Phatty for the mono stuff such as bass and the odd leads, sweeps.
For bass and leads, i wanted more of a dedicated synth, so i was looking at the SE1X vs the Moog Little Phatty. Comparing both the specs and price.
The SE1X does have 3 oscillators vs the 2 oscillators in the Moog LP. But the LP does have an Overload button (Phat button as Moog call it), which adds a growl / bite to the sound. The Overdrive is optional on the SE1X, and it is supposed to be a nice touch as owners will tell you. The SE1X also has a 2nd 12db (as well as the 24db) filter over the single 24db moog filter on the LP.
Im sure some real users are going to chime in and give a better break down on the SE synths.
As for the Poly side, well i am saving my pennies right now for a Code 6/8 for later this year. I plan to use it along side my A6, which has it's own desirable character. The Code and Omega are both 2 Oscillator per voice synths (so is the A6). The Code does have a new Sine wave on oscillator 1, just like the newer SE1X, which should cover your bass needs perfectly should you decide on a Code.
And personally i prefer single oscillator basses anyday of the week, and both my A6 nd LP deliver very well. For leads, 3 Osc's allow for thicker sounds, but bass tones end up with that beating effect (cool for leads), which is why single oscillator basses are more solid and consistent.
What i am trying to say is, you may want to try out a Little Phatty and see what you think. It also costs less for a genuine Moog tone (if you like that). For lead sounds, the 2 oscillators do pretty well and if you record (or multiple layer) another stack of two oscillators (with perhaps different octave settings) you end up with 4 oscillator lead sounds - not bad for a little workaround. Bass is also a strong area for the LP.