[JamesC]

Single engine service ceiling numbers are attached for a 1971 (non-turbo) Skymaster. Just to illustrate as an example, today it is +70 deg F at Sedona airport (4830 ‘ asl) and say an engine fails at max gross after take off. In a turbo model you will be climbing at ~ 240 fpm. According to the attached table, in the 1971 model you will have to descend. Obviously those who fly the non-turbos already know this. This also implies that say it is 80 deg F and humid, you will be lucky to maintain even 4000 feet at max power if an engine fails. Anecdotes re turbo vs non-turbo are entertaining, but the only anecdote that really matters is the one that you got yourself into when those Swiss cheese holes line up.
So like anything in flying you have to weigh the pros and cons (for turbos cons include the weight, the cost of maintenance/repair/overhaul, you have to be more careful with MP settings and treat them right, and it’s another thing that can fail in flight), and make your choice. Personally I chose turbo for all the reasons in the P337H tables attached earlier.