Let me ask this directly. Is it sufficient to work in Inscape with Wacom Bamboo to make professional calligraphy art works or it's better to buy Wacom Intuos Pro Pen & Touch Medium tablet or even small Intuos would be enough? What is your experience in that, guys?

Hi.

Your direct question maybe is a bit too straight to be answered right.
Maybe you better ask a professional calligrapher of his/her tools used.

One problem to answer your question is that you ask for professional tools.
I saw professional calligrapher who used a credit card to draw large letters, and small pieces of papers.
Actually it is not the tool you use but how you are using it.

Also, by the profession it all comes out as business.
You can go wild and paint as Pollock -or even wilder-, as long as you can sell it it will be professional work.
Thus profession is not always equal with high quality.

There was a topic here around the professional/amateur works where the original poster even claimed inkscape is not for serious business.
It can be said that the professional field is based much around illustrator though.

As I see it, inkscape's calligraphy tool is what makes quality calligraphy questionable, no matter tablets used or not.
Again, you can use it with or without any devices, quality, artistic value is based on how you use your tools, and has not much to do with profession.

So better ask someone directly, who does exactly what you would like to do.

There`s not much to add unless you could add some examples of calligraphy which you would like to create.

Inkscape tools are tameable, both pen and calligraphy, but it mostly depend on what you`re after.

Nowadays you may find all kinds and sizes of tablets and pens but unless you could afford Cintiq, you`re good with any kind of tablet. I`ve heard from other tablet users that smaller ones are more comfortable than large ones. Might not sound logical but after a few hours your hands can`t be dry and clean (and "light") as they were - which in most cases includes some kind of gloves or other accessories ,)

Still, bamboo might not be capable to provide you with Bristle and similar brushes in other graphics oriented apps ,)