Active crossovers are like lusting after a new Porche. They go faster and handle better but are not near as practical as a BMW M series sedan. The point being that a well design passive crossover can give you tremendous satisfaction. You don't hear may Jim Salk HT-3 owners lusting after the DEQX active model. That's because Dennis Murphy's passive crossover design is elegant, simple and works darn well. So, do Dennis' other designs. Historically speaking, Phil Bamberg was one of the mentors in speaker design in the Madisound forum.
I like that Phil with BESL provides a simple upgrade path. You can start with the more economical passive System 2 MTM and later use the same cabinet and upgrade to the System 5. If you wish to try active, you can keep the passive crossover and pay the nominal fee for the DCX2496 and take advantage of having Phil (Mr. Perfectionist) Bamberg spend hours with you making sure it is setup optimally to suit your room and taste.
Keep in mind that you have to plan to have a subwoofer to integrate with the System 2, 2.5 or 5. They are sealed monitors so they don't extend down to the 40Hz region like the Ellis 1801 which is ported. There are tradeoffs but don't follow the simple notion that ported is better than sealed or vice-versa. It all depends on the designer and the execution. With Phil or Dennis (Jim Salk and Dave Ellis), you have both.
Yes. I did have a Ellis 1801 and I do think about it occasionally. Had I had more room and money (at the time), I would have kept it. I had a lot of sentimental value and helped sell 4+ sets as people stopped by my place to hear them. For a simple 2-way, I was very happy with the 1801, AKSA amps and BentAudio passive. I'm now very happy with my primarily HT 5.1 system that does a good job with music. My wife made it very clear that she didn't have the patience to wait for me to build my dream active system. It was getting very complex. Having a simple system became very attractive.
You live in a small apartment, have you thought about building a killer headphone system and a simple stereo system?
Oh and by the way, if your heart is set on going active, then go for it. The UcD amps are a great option. You need to audition the BESL's, Jim's HT-3 and SL Orion's.