Analytic vs Synthetic forms

Munster Irish is well known for having 'synthetic forms' for verbs. That is, where Connacht or Ulster Irish would say, Tá mé go maith, in Munster, the "I" is absorbed into the verb itself, Táim go maith.

From some of the older texts that I come across, this formation is often called 'archaic', or 'ancient', and the modern language was supposed to completely adopt the new 'modern' analytic endings. I don't think this is quite the case, although I often see mention of Munster Irish as holding on to 'older' pronunciation and forms. I mentioned this back at the beginning of the blog.

I assume that the forms are mutually understandable - that is, using the endings as Munster would while speaking otherwise flawless Ulster dialect will be understood, but how weird would that be? Like many learners, I'm getting a mishmash of different dialects because of the variety of sources I have to listen to - and believe me, listen to an hour of Radio na Gaeltacht and you'll hear enough variation in the language that you start to think you'll never get it!).

Any native speakers who can weigh in?

Unilang has a nice complete verb table showing the Standard Form and Munster form. The rest of the google results for Munster show up as copies of the Wikipedia page. But, trust Gramadach na Gaeilge to have more linquistic info that you could ever want.