I blew 1000 pounds of cellulose insulation in my attic in about 4 hours. Cost was $500. It's a pretty easy though dusty project, kind of like blowing out dust from a vacuum cleaner. Cellulose is much nicer than fiberglass and better R-value. More info if you like or hit youtube.

Or read some reviews from what I used...

https://www.homedepot.com/p/Greenfiber-All-Borate-Cellulose-Blow-In-Insulation-30-lbs-36-Bags-INS765LD/300584221

Mini-Split has once again seemingly plagiarized an answer from another site without attribution. (Or does he suggest they copied him, this time?)

Exactly same general answer

Why batt ceiling insulation covers over roof joists is that is full width material so if your joists are 24” on center your material is 24” and will be a little squished between studs but should expand to fill in above the wood.

blow has air blown into it when it travels down the hose but when you have to walk or crawl through it deflates reducing air spaces and insulation value.

You might look into radiant barrior sheathing applied to rafter part of truss(right under sheathing) it really works well in hot summer climates. Then there’s spray foam which puts your ducting in your building envelope and makes a seal that fiberglass and cellulose never will.

I had the same experience in coastal Calfornia, a switch from cedar shingles to a composite roofing material significantly increased late afternoon heat radiation from the attic, even though our attic insulation was at code. Even with beefed up ,attic venting. A large insulation contractor in my area suggested fiberglass batts, talked me out of crawl space insulation (no bang for the buck), and got the job. The effect is huge. More so in the summer than winter because the temperature difference between the attic and the house interior is much greater in summer than in winter.

Make sure you have enough attic venting too, that matters.

The thing about blown in is that baffles need to be carefully installed so as not to block eave vents, if present.

I'd go with batts. They are more expensive but there's a reason for that! Your Pro/Con list is pretty accurate although the bats will protrude above the average ceiling/attic joist so there should be little or no negative effect on R-value.

Thanks everyone for the helpful comments.

Yes. We have a ridge vent on top of the roof and soffit vents for intake. The intakes have been painted, maybe more than once, and many of the spaces in the meshes are visibly reduced, some blocked completely. So cleaning (if possible) or replacement of the soffit vents is definitely on tap. Though the roofing contractor estimated the number of soffit vents is sufficient, I am not sure this is the case, and the blocked vents should have been flagged. (Otherwise, the roofing job was fine, though I wish we had more information upfront on the potential for the summer heat problem. We may have chosen a lighter roof color or one with more reflectivity of solar heat. Had no idea how easily the wood shake roof "breathed".)

Another potential mitigation--when we get some solar panels (another project some day), the hottest part of the roof facing the sun will be shaded.

End of summer update. We had R38 Batts installed at the beginning of July. The improvement was immediate. Even on the hottest of days, the inside of the house never really got above 75, and the whole house feels much cooler, probably because we are not exposed to the hot ceilings. Should have done this years ago! We're looking forward to seeing how our insulation makes the house different when we start heating.

Glad you've had good luck. As I mentioned in my first comment above, where I mentioned I did the same as you under the same circumstances and for the same reason. As above, I have found the benefit is much greater in the summer than in the winter. Because the temperature difference between the interior and the attic where I am is much greater in the summer than in the winter, so the insulation is more important to have. A 40-50 degree or more summertime difference wouldn't be unusual. In the winter, the difference is typically not even 30 degrees at worst and then only for a few hours overnight, until sunrise starts to warm the attic.

If you're inland with higher summer temps and lower winter temperatures, your experience could differ from mine. Good luck.