Looks like there haven't been any trip reports from the CRJ-550 on this thread so I'll give a brief description of my out-and-back DTW/IMT the past couple days.
Outbound: DTW-IMT on 1/13/25, we departed from gate B10. There were approximately 30 pax, a bit higher than expected because the previous day's flight had been canceled. As a DM the upgrade for myself and my companion (on a separate PNR) came through 5 days out, along with a couple others. By the time of boarding F was full (including at least one from the prior day's canceled flight). Boarding was very smooth and quick. One thing I found odd was they announced they may run out of overhead space for bags and they might have to pink tag. I didn't see that they did any pink tags in the end, but can't be sure.
Sat in 3A on the outbound. Seemed like the most leg room I've ever seen on a non-bulkhead recliner, and the seat lines up with the window. One surprise was no power outlet at the seat. The spot that typically has the outlet had a plastic plate over it. Only traveling for one night with a somewhat overloaded backpack, but it easily fit under the seat. Between F and C+ there were two closets on the starboard side and one on the port. There was one shelf and looked to hold approximately three standard carry-on rollaboards on the floor and three more on the shelf per closet. There was a fourth closet in front of F next to the galley but it looked to be a bit smaller.
There was one flight attendant, and she provided the typical service for a short (344 mile) RJ flight. Choice of PDB in F, followed by a choice of beverage and snack basket in the air. C+ was offered beer or wine in addition to water, and the back got water only. This plane had no potable water, so no coffee or tea. The self-serve snack area was not stocked.
Wi-fi was announced as available but not free. It did not work.
Deplaning in IMT was onto the snowy tarmac at about 5 degrees F. The ramp crew had trouble with the boarding ramp, so we used the airplane's built-in stairs.
Return flight 1/14/25 IMT-DTW. IMT is a small outstation so they opened security about 10 minutes before boarding. There were approximately 15 pax. Again the upgrade came at 5 days out. Boarding was smooth and quick. Four total people in F and approximately 11 in the back. Everyone that was in Main got moved up to C+, I assume for weight and balance. This happened on the seat map around a half our to hour prior to boarding.
Sat in 4A on the return, which is a very private spot with the closets to the right and behind. Only drawback is misaligned windows so it was hard to see out.
Service on the return was identical to the outbound including no potable water and no wifi (I didn't grab ship numbers but I assume it was the same one).