I think that by your model year, they had the guide problems fixed.
I certainly wouldn't do anything if there are no symptoms of any problems. Does your Benz burn ALOT of oil? That's the primary symptom of guides that need replacing.
It is getting time to replace the timing chain though. You have a single row chain that has been know to break and bend the valves and sometimes break the cam. You can roll your own chain in, or have a shop do it for a few hundred dollars.
'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)