Chimney Cleaning for Fireplace Xtrordinaire with Catalytic Converter, Have I Been Too Trusting?

We have a 36" Fireplace Xtrordinaire (has a catalytic converter). We also have a nearly 3 stories high chimney which I have been unable to find a sweep willing to climb. I have had a couple of sweeps tell me this fireplace can be cleaned from inside the house, but I fear they told me this because they didn't want to break out the tall ladders and brave the height of our chimney.

I was hoping someone with more knowledge could either confirm my fears, that the highest portion of our chimney is likely not being adequately cleaned, or put my worries to rest by confirming this type of fireplace need only be cleaned from the inside.

Any thoughts shared, greatly appreciated.

It is possible to clean from he inside by adding extention lenghts as it goes up the chimney. Whether standing at the peak adding lenghts or at the base it is still going to take the same amount of lenghts. The brushing action up and down is the same too

You might be able to get a brush past the bypass damper, but I usually dismantle the baffle when I clean those any way. If you watch them do that then you're probably fine. The only disadvantage is that you don't get the top of your chimney inspected. You might want to make sure they do that from time to time.