I don't think the discos are "passe" at all. I have a Condor, a Talon, a Marauder and I just bought a disco 2 weeks ago.
As far as comparing the Marauder and the Disco that's like comparing apples to oranges.
The Disco is just what it appears to be....... a simple PCP that a person with no PCP experience can just take from the box, air it up and start shooting. It's accurate and powerful and very simple,,, and that's just what it was designed to be.
While you can of course just take a Marauder out of the box and start shooting without adjusting anything those myriad of adjustments are still there in case you need or want them. However,,, while the adjustments available on the Marauder are not "rocket science" they still do require a basic understanding of the mechanics of a PCP.
The airgun community has of course come up with all kinds of "after market" products for the disco which now allow you to adjust the trigger, the power, the shots per fill, etc,,,, but in it's stock form the Disco was designed to simply be a "out of the box" PCP for those looking to enter the PCP arena. However...... even though in stock form the Disco is "simple"...... don't underestimate it's power and accuracy.
I just picked up a .177 Disco with pump from Airgun Supply for $249 and even though my Air Force rifles and my Marauder really rock..... I have to say I love my little disco and plan on doing quite a bit of small game hunting with it this year. It's nice and small and light,,, it's powerful, it's accurate and it's nice and simple.... which is just what I wanted. If I want to play around with Hammer stroke settings and such I'll go play with my other PCP's,,,, but if I just want a gun to grab and go hunting that's easy to pump up and easy to operate then I'll grab my new Disco... :)
I'm not trying to steer you towards a disco and away from the Marauder.... If you get a Marauder I know you'll love it, they're great rifles.... but so is the disco....
Which rifle you choose of course has to do with your needs, your desires,,,, features of each,,, and of course price. Right now at Sunshine airguns and Airgun Supply you can get some smoking deals on the disco.
Ok, I'm done... can't think of anything else to say except I personally think the disco is still a great little PCP ,,, especially at the prices they're selling them for now and I don't think the disco is "passe" at all.....
JEff