Is the XV80 a communicating model that has been taken back to 24v or is it a straight 24v?? If a comm model running 24v, you have much more flexibility. You can keep comfort r on the front end and eliminate on the back end (cond shut down). You can't do this on straight 24v. Also, you can set your 1st stage % of airflow.....but not if straight 24v. If straight 24v, I would turn comfort r off. The fan delay reevaporates condensation back into the airstream.

Your stage two doesn't appear to be operating properly. Based on what you said, you are getting somewhere around 12-14 degree td across the coil. I would look at getting the system running properly in both stages @ 350cfm per ton for a 5 ton.......once done, if not satisfied, look at other options.

Thanks. That helps. How can I tell is the XV80 is communicating taken back to 24V. The contractor says is is, but from everything i have been able to dig out, I can't find what to look for (control board number, etc.) that would tell me. I know the installation sheet that came with it does not cover any of the fine-tuning that you have mentioned in your post.

the NON-communicating furnaces have a bank of small dip swithces ( I believe 12). The comm furnaces will have a bright orange "user interface" that looks like the thing in the middle of your cell phone, but bigger. Arrows on all four sides w/ an enter button in the middle. There is also a very visible L.E.D. screen above the orange buttons.

I have a NON-communicating XV80 furnace then, because i have become well-acquainted with the dip-switches.

1st stage on your outdoor unit is roughly 70%. Non-comm furnaces are set up to operate Y1 (1st stage cooling) and Y2 (2nd stage cooling) with the dual compressor models (50% 1st stg, 100% 2nd stage). Therefore, you do not wire through y1 & y2 on the furnace or you will have the wrong airflow (this is why many contractors miswire). When someone uses a humidistat, the airflow is dropped to 80% on this furnace. When mated w/ a two-step single compressor, Trane uses the humidistat set-up to achieve 1st stage cooling airflow. Because 1st stage compressor is 70% and airflow is 80%, you generally see a slightly larger temp drop on 2nd stage. You have the opposite. It is not perfect, but you can count the flashes of the green light on the control board in the furnace. Each flash is ~100cfm. Depending on where you have your dip switches set, you should be able to check for proper airflow. Take of the door of the furnace and hold in the door switch and count flashes. You'll get a 'quick' flash on the last one for partial 100cfm.

Many many XL16's are miswired. The W14 jumper on the board also must be cut. Y1 on the stat should go to Y on the furnace (not Y lo). Y2 from the stat goes to BK on the furnace. A jumper must be added between R and O on the furnace terminal strip. Visually check your wiring and airflow. If not correct, call your contractor back out. Nothing will be connected to Ylo on the furnace!

BTW, I had forgot to add that according to the DAT sensor temp. there is currently a 15 - 19 degree drop in temp across the coil at the current speed (which turns out to be about 90% of what the 350 CFM setting for a 5 ton would be. With the system set to a normal 5 ton at 350 CFM, the drop is 13 - 17 degrees.
Interestingly, the setting for airflow on the XC80 communicating furnace does not have only the 350/400/450 selection, but one lower setting of 290 CFM. This is the unit I do NOT have, but I was surprised to see the CFM rating for each of the "tonnage" sizes with this low option.
Any additional feedback is surely welcome. I am trying to have an intelligent discussion with contractor, who is willing to listen and has said so.

I checked the wiring and it is correct. Thank you for the tip. YLO is not used. R & O are connected. The W14 jumper is cut. Thanks for the explanation. The wiring makes compelte sense now. BTW, I have not even checked the stage 2 operation. The figures I gave were for my manually trying to set air flow of optimal humidity reduction and as close to optimal energy efficiency. My previous message has the details. THANKS AGAIN. I never knew buying a new AC would be so confusing.