Yes, Lamy ink is perfectly fine ink. As a general rule, expect any ink made by a pen manufacturer to be really easy on a pen. Besides Sheaffer Skrip Blue I also have a bottle of Aurora Blue I keep at the office and have had no issues with it.
Please note that I'm not knocking inks made my non-pen manufacturers, just in my personal experience I'm willing to trade vibrancy of color on the page for ease in pen cleaning. Purely my preference, I don't believe that inks made by Noodlers or Private Reserve will actually damage pens.
Its worth a shot, but poor ink flow could be because of all sorts of issues. Misaligned tines etc. If the pen is worth it there are a number of nibmeisters you could pay to fix your pen for you. Writing with a pen tuned by a nibmeister, like John Mottishaw at nibs.com or the now retired Richard Binder, is a fantastic experience.
I love Montblancs. The tri-tone nibs on the 149 are visually the most stunning nibs made, IMO.
If you really want to go down the Japanese pen rabbit hole start looking into Nakaya pens.