Hi Bruce,
I have been using my Searwood for a year and a half now.
My perspective of your questions:
1. I am reading on this forum about runaway temps when you increase cooking temps after smoking. This is something I do all the time. Lower for more smoke and then increase to desired temp. - I did have the issue of the temp going up after going from Smoke Boost to a high temp 350+. But it hasn't been an issue for me.
2. Manual mode? Only for the griddle? Not for smoking at all? The weber video and website is useless. - I have never used the manual mode. As I understand it, you don't need to only use it with the griddle. You can use it if you are grilling, say hamburgers, and keep a constant heat with the lid open.
3. Does the unit have a smoke only mode? - Yes Smoke Boost. Setting the temp to 180 degrees, is the smoke mode. I use this all of the time to make beef jerky.
4. I'm already not liking the computer that runs this Searwood. My Pit Boss had a digital dashboard but it was fairly straight-forward. - I use the app of my phone all of the time to check on what's cooking and to raise/lower the temp. I haven't had any issues with it.
Please tell me to return it or keep it. I was planning to smoke an 8lb brisket (split lengthwise). - You are the only one who knows what will work for you. But, the more I use mine, the happier I am with it.
A few tips:
1. Weber offers a 3-sensor plug-in probe that I use,
https://www.weber.com/US/en/accesso...pe/wood-pellet-grill-accessories/3400321.html. I have found that it is with-in a couple of degrees of what my Thermopen reads.
2. I use the top rack for the vast majority of my cooking. I had a 24" x 14" expanded metal rack made for my Smokefire. I did a couple modes to make it work with the Searwood. On long cooks I almost always use a water pan below what I am cooking. It adds moisture to the cook and catches the drippings to make cleaning up easier.
3. The rotisserie feature is something that most pellet grills don't have. I have cooked chicken, up to a 14# turkey, and a boneless pork butt, my favorite. Check out the The Basement Hangout Youtube channel,
https://www.youtube.com/@TBH-Grillin. The have cooked many things, popcorn to brisket, on the rotisserie, some good, some bad.
4. Use good quality pellets. Good quality will burn hotter, last longer and produce less ash. I am exclusively using the Knotty Wood pellets,
https://knottywoodbbq.com/product-category/knotty-wood-bbq-pellets/. They can be ordered from Home Depot and they pay the shipping.
I hope this helps you decide what you want to do.
Doug