I think Phoenix at Sunday lunch is ok noisewise/comfortwise once you get seated. There will likely be a significant wait at peak hours but once you get a table I feel like the spacing of the tables is reasonable and the noise level does not inhibit conversation. Not quiet but you don't have to shout.
Had a very good visit to Phoenix a few weeks ago, better than the previous couple of visits. The basic dim sum items (shrimp dumplings, shrimp crepes, etc.) were well done. Skins were a good thickness, ingredients were fresh. AND they had soup dumplings (xiao long bao). The soup dumplings had a reasonable amount of soup, good flavor, and the skins were respectable. Not close to ones I have had in other cities but probably the best in Chicago (supposedly they have them at Shanghai Terrace but I have not tried yet).
One tip for soup dumplings or any other item is to ask the waiters (not the cart pushers) for whatever items you want but don't see. They are very accommodating and another advantage is that the items will generally be freshly prepared when you get them.
I'd been a little down on Phoenix but really enjoyed the last visit and would recommend highly.