In irish one has what you may call 'pausa' and 'allegro' forms for words, that is, a pronouciation like one would have in the dictionary (isolate/pausa), and then different forms in speech that depend in how rapid speech is or other factors (allegro).
As far as I can see, no full outline of allego factors has ever been fully and holistically developed.
Here:
http://www.smo.uhi.ac.uk/~oduibhin/sf/ you will see variances in the preposition pronounced before a verbal noun (what you call a present progressive verb, I think). In the dialect books there is a varience too.
As a rule of thumb, I personally find it more pleasing to the ear to use the removal of g as it makes the learner sound more serious (at learning) as they must switch between braod and slender in context, and a learner is less likely to do that. using 'uh' bypasses that issue before consonants.