My Dad's 1990 190E 2.6 has about 200,000 miles and barely uses any oil. Top end work is a ways off yet.
But, that car has been in our family (I owned it as the second owner) since about 55K-miles. Synthetic oil, frequent changes, etc. I anticipated that the top-end would come due at about 200K-miles, so maybe we're also just lucky.
The premature-wearing guide problem on the M103 was fixed long before 1992. The only reason your guides would be worn early was operating conditions or long oil change intervals.
Also, $2500 for a top-end on the M103 is REALLY high. Most estimates run $1,000-$1,500.
1998 C230 "Black Betty"