In the past, Nice to meet you was considered the proper response to an introduction or short conversation with someone new. But like everything else, language changes and "Nice meeting you" is perfectly acceptable.
Since great is not on the list, there is no reason it can't be followed by a gerund, so, again, you're safe there.
I have not been able to find the rule you gave. However I have found a list of adjectives that require the "to + infinitive". They are:
adjectives expressing emotion, e.g. angry, disappointed, glad, sad, happy, anxious, pleased, surprised, proud, unhappy, confused, befuddled...
adjectives of ability or willingness, e.g. able, unable, due, eager, keen, likely, unlikely, ready, prepared, unwilling, willing...
adjectives used to express opinions, e.g. to give opinions: difficult, easy, possible, impossible, hard, right, wrong, kind, nice, clever, silly, foolish...
adjectives referring to difficulty, e.g. difficult, easy, possible, impossible, hard
when using the preposition "of" with other adjectives:
It’s kind of you to help.
It would be silly of him to spend all his money.
This was all I could find. Sorry.
Source: British Council