Both brands deliver high-quality writing instruments; in a side-by-side test at a dealer testers found the Caran d'Ache Léman M nib to be finer and better suited to small handwriting than the somewhat broader-falling Montblanc M. In general, Montblanc nibs vary in line width and ink flow due to manual finishing; a nib test or exchange within the swap period is recommended. For everyday writing a moderate weight is comfortable — very light pens lead to cramping, very heavy ones cause fatigue. The Montblanc 145 (Chopin/Classique) is regarded as suitable for daily use, blot-free and popular; anyone who values a somewhat more flexible nib should consider alternative makers such as OMAS. Ultimately the individual writing feel at the dealer decides.
Related pages on fountainpen.de:
• Montblanc Meisterstück 145 (Classique): https://www.fountainpen.de/c-montblanc-meisterstueck-145-en.htm