Man, Ted, did I miss something? I'm really sorry that you mistakenly assumed that my post was somehow specifically addressing something that you may have said or not said! Duh?
It should be clear that my comment paraphrased as your "having bad things happen if the line breaks" was in reference to the rather short time period between a failure and the consequential damage that might occur. You could consider that oil circuit operating pressures, the oil pump operating volume, engine speed, and the total engine oil volume and come to the realization that at highway speeds your engine could be virtually oil-less in less than a minute. Perhaps you drive with your eye constantly affixed to your OP gage and idiot light , if so then you will undoubtedly be able to respond in the event something happens and mitigate any potential problems.
My comments regarding the wisdom of those who opt for the adapted drain plug return method was actually in reference to an earlier mention concerning VW installations, but would apply to any similar installation, you seem to have come to that same conclusion all on your own. If you read my comment regarding "monitoring" it should be clear that there again is no reference to any comment you may have offered or not offered, I was speaking simply of the difficulty of being able to regularly and effectively determine the integrity of any modification that is under the vehicle and possibly obstructed from view by such things as the belly pan on a 126 car. Perhaps your position is that any such modification of questionable design is better off secreted somewhere out of sight rather than an installation that has been sited with deliberate care to facilitate an ease of monitoring. Your choice to modify your drain pan may better suit your thinking in this regard. I could be noted the engineers who designed not only your vehicle but so many others apparently decided that in the case of oil circuitry components, particularly those that are outside of the engine itself, should be very high quality specifically engineered to prevent failure that could cause catastrophic engine damage i. e. your oil cooler hoses, it is probably no accident that these components are high strength and fitted with swaged fittings for a secure positive connections. It could certainly be worthwhile to ensure that any add-on external oil circuitry component meet or exceed this original level of design for piece of mind if for nothing else.
Last but not least regarding my original premise. If you bother to reread my comments regarding the OEM canister filter you would know that I simply pointed out that a bypass filter has been designed and integrated into the oil filtration circuit already, the filter canister that fits in the filter canister housing attached to your engine consists of two elements, the full flow and the bypass flow. The engineers at Mercedes Benz where actually capable of understanding the benefits of bypass filtration and even as far back as 1982 integrated that element into their overall design, rather than leave it to some aftermarketeer! Having read some of your earlier posts, Iíll assume that you should be able to check your CD Manual, Engine Manual, Main Function Group 18 Engine Lubrication, Sub Function Group 005, Oil Circuit, Oil Pressure, Pressure Relief Valve, and Oil Filter, PDF page 3 of 7 provides a canister filter photo and a description, while pages 4, 5, and 6 of 7 provide comprehensive schematic diagrams of oil flows and every oil circuit element! F*#%ing DUH! Happy Motoring and Good Luck!