Would I lend my W113 to a stranger? No. Under any circumstances.
But the question wasn't specific to a W113 or other classic car... just "pride and joy"... and, for example, my '65 C20 is one of my pride and joy vehicles.. and I'd lend it to a stranger in return for the reverse lend of a brand spankin new F250 longbed Heavy Duty, 4WD, 4 seater, leather interior one.
Tosh... I think the real issue to most would be whether it's a total stranger or not. By the time you get around to lending a "pride & joy" vehicle to a stranger, it's more likely than not that they would be something less than a stranger by the time any deal could be consumated.
Longtooth
67 250SL US #113-043-10-002163
'02 SL500 Sport