Any wannabe arborists trimmed their own trees?

Yes, but climbing gear is less efficient than tree gear.  We did a tethered/hinge drop between 2 houses. (Top of tree was dead and brittle, so we swung the whole top on a tether).  We were successful, but probably a really dumb idea in hindsight.

Redundancy is key, most climbing gear is light weight and won't survive a chainsaw knick.

I have used the slingshot/anchor/ascender method a few times.  Make sure you have a ground person, and some confidence with a saw (a dull or loose chain are bad).  Sucks to get your bar pinched up in a tree!  Climb without your saw, anchor, then haul it up.  Definitely recommend Kevlar chainsaw chaps.  It's very physical work, high risk, low reward, so keep it all in perspective!

For fun, Google 'chainsaw fail'

Trees, depending on their shape, lean, scarring, internal rot, twists, etc.  Might be storing a ton of unforseen potential energy.

You can certainly do it yourself; what you pay big money for an arborist to do it is the "guarantee" that it'll be done safely, and the insurance they have to pay out if shit goes wrong.

Use two tie ins when you're cutting, make sure your rigging line isn't running over your climb lines, and DON'T USE A CHAINSAW UNLESS YOU KNOW HOW. They're so flipping dangerous and learning how to use one in a tree is just asking to get hurt. 

I should add that my 250lb friend had worked as a ground person in his younger days. I planned the work with him and he sent gear and water, etc... up to me. Also kept an eye on me for safety sake.

I used to work on the ground with an arborist. Not much climbing but plenty of saw time. Done some climbing work at my own house as well, pulled a few trees over with the truck. Hard and scary at times, but rewarding. 

1.  Get some chaps, they’re like $50 on Amazon.  Cutting your femoral is one of the quickest ways to bleed out. Check out this video (mountain biker jugular injury). 

2. Consider renting a lift from Sunbelt / United or whoever. Probably $300 for the day, but eliminates a lot of the climbing / rope rigging - assuming access / terrain permits it.