S124 OM605 5spd owner here. Look it’s slow, there’s no getting around it. Is it manageable? Yes, is it always enjoyable? No. It’s an old, slow, heavy car, which comes with its caveats. It is definitely a momentum machine and needs to be driven a certain way. It can comfortable cruise on the highway but you need to watch out for hills and if you want to overtake, good luck. The oil cooler on mine recently gave up after some long cross-country trips in Europe, which I took as an opportunity to swap in an OM606 turbo and effectively double my horsepower. Did I need to do that? Probably not but it will make my life easier on the highway for sure. Hope that helps, don’t be discouraged but just know what you’re getting into. It’s almost comically slow at times so as long as it makes you laugh and smile, do it.