Adjusting to a new pen is generally necessary; in most cases the cause lies not in the writing instrument but in user adaptation. For heavy writers who have to mind tendinitis, the larger 149 is ergonomically often better, since the thicker body strains the arm tendon less. An M nib should not scratch on normal paper; problems mostly occur on very inexpensive paper or when the nib tines do not stand cleanly to each other. Good papers like Clairefontaine are recommended. Anyone with a nib-swap guarantee at the dealer can also have the nib width adjusted afterwards in the boutique without problems.