You have your answer; MDF is ok at ceiling level. It could probably hold up in rooms that aren't heavily used, but why go through all the installation and painting costs for a product that doesn't hold up to active family life or pets.
You can buy wood doors that are well made and look good and that don't cost a fortune if you stay with softwood choices. You can paint these with a semi-gloss marine grade paint that won't chip, crack or fade. A regular semi-gloss paint will chip, so use a marine-grade.
I did my prior house in a softwood door and used semi-gloss marine grade paint. The doors always looked good with heavy dog traffic.
My current house has stained and poly sealed hardwood doors that act the same as the painted softwood doors. Hard as a rock, resists scratching, pawing, cracking, holes.,,,,stands up to punishment.
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Goes with BM Shoreline
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