After replacing the spool bearings with Ceramic bearings, none of my other reels can match it in terms of casting distance. It can cast tiny 4gm lures against the wind with ease.
Another standard upgrade that I did was a new Smoothdrag carbontex drag washer. Right now, I installed them dry. It felt smooth as it is without using Cal's drag grease or similar grease. At first I thought that the carbontex drag washer was enough but I read somewhere from Tackletour that smoothdrag has stainless steel washers for Daiwa millionaire so I ordered a couple of sets. Originally they were for my Daiwa Luna and millionaire but after trying the top most washer into the Sol, I noticed a significant increase in drag pressure and smoothness. I think the increase can be attributed to the size of the new washers. They are bigger - fits almost flush into the washer bay of the main gear.
Because of the increase in drag, I am confident in using the reel in Inshore fishing. The only drawback is the increase in likelihood of corrosion in the bearings. Daiwa Sol was originally intended for freshwater fishing so they were released without CRBB (Corrosion Resistant Ball Bearings). That's no a problem since you can easily buy high quality bearings online. I already replaced the bearing in the cast control and it seemed to be holding up ok after a few sessions in saltwater.
I think this reel is an indispensable reel in my arsenal. It's not only for finesse fishing (light lures and light lines) such as for dropshotting, weightless plastics, and really light jerkbaits and cranks but it can also be used for heavier line and lures such as spinners. Since the gear is only 5.8 (somewhere around 26" per crank). It's slow but it's powerful.
Too bad Daiwa has discontinued this reel. I personally think there's none out there that has the same value in terms of price and quality as this reel.
Next upgrade is the CRBB bearing on the worm gear and a new handle and drag star from the Alphas Type-R.