I have 16 CRJ-700ER's and 18 CRJ-200ER's in the fleet. The 700's are at a minimum of three rotations a day and bringing in between 20,000 to 120,000 on the three rotation aircraft, with a maximum of 220,000 on a 6 rotation aircraft. Geographically, I'm in the middle of nowhere, meaning my utilization on most aircraft will peak at 3 rotations. When we had the fuel spike a few days ago, I saw the margins drastically decrease, making only about 20,000 to a loss for most aircraft.
The CRJ-200's are worse. Some of them are already on really crappy distant routes, simply because I'm running out of dots to connect while waiting for the rest of my Airbii. I had almost a full screen of red on the -200's during the fuel spike. I'll be replacing them with 700's in the future once I've gotten my A32X routes sorted, and hopefully I've underserved the market enough to make money on the extra passengers.
I've noticed -200's start to fall flat on their face at around 700NM segment lengths, and CRJ-700's around 900NM. I haven't bothered with the LR options because if I'm flying a CRJ-700 1500 miles, I can only schedule two flights a day, and I will run very narrow margins.