The MM 141 & 181 classes were turned out over a decade ago with good detailing and excellent running (particularly slow running characteristics).
By comparison with the some models in the last couple of years, there may be a few differences.
They do come DCC ready but not sound ready insofar as they do not have an inbuilt speaker which functions as soon as a compatible sound chip is installed. A sugar cube speaker seems to function best and can be wired in although it is not PnP.
They have directional marker/running lights and headlights which change automatically with the direction of travel but do not have cab lighting like the MM071 class (iirc). The rear lights of a lead loco or the front lights of a trailing loco can be turned off if two are running in consist but the switches are somewhat inaccessible as they inside the body shell versus the larger 071 class which followed where they were located underneath the loco and could be switched with a fingernail or small screwdriver blade.
To access the interior the 141/181 body shell has to be removed from the chassis which means very carefully detaching the handrails along the loco sides from the cabs, and prizing the body off which can be slightly tricky. It comes apart as the main body with one cab as one piece and the other cab as a second piece. When replaced, some found that the cab did not fit back as tightly to the chassis as factory fitted and had a tiny (<1mm) gap which was a minor cosmetic issue. In short, it's not a matter of deciding to link two locos up for a quick spin and then detach the consist again.
When new, they usually came with a 'bag of bits' which included horns, skirt (to be 'blown up', or just fitted where the coupler is at the 'non functional' end) and various hoses. These are fitted by the user as needed and enhance the look of the loco but may be missing when purchased secondhand. One of the members did a nice tutorial on how to fit the front skirt and then have the coupler come through it but the photos have disappeared from the site when Photobucket withdrew support from linking to other websites.
More recent offerings are often sound compatible out of the box, with better access to switches e.g. through a roof panel so there is not need to remove the body shell, have cab lighting and maybe some additional cosmetic nuances.
With all that being said most will agree that there are VERY fine locos. If you cannot acquire what you need from Dave then take solace in the upcoming MM 121 which seem to have all the perks