I am just getting started woodworking. I just built a toy chest for my daughter and am looking for smooth crosscuts on hardwood trim. Is it worth going to the 80 tooth for crosscutting? Thanks for your help.
"It depends" is really the answer. Tooth count is one aspect, but there are many other factors that are not always created equal between various blades. The tooth grind and geometry play a big roll too. As does the basic quality of the steel, the sharpening, etc. If all other blade parameters are equal, more teeth will give a cleaner cut, but they also pose more resistance, more heat, and are more prone to burning...60T to 80T for a 10" blade is about the sweetspot. The LU91 uses an Alternate Top Bevel grind (ATB), which is one of the cleaner cutting grinds that also has good tip life, and combines that grind with a negative hook angle which will reduce tearout. A more positive hook would cut faster and more aggressively, but would also have more tearout.
You should get fairly clean cuts with the LU91....I've never heard a complaint from someone who was disappointed with that blade. Blades like the Infinity 010-060, Infinity 010-080, Freud LU79 & LU80, Forrest Duraline, and Forrest WWI, use a "Hi-ATB" grind that has an even steeper bevel across the top of teeth for even less tearout than a standard ATB grind. The downside is slightly faster wear, but for hobby use it should still last a long time if you keep it clean (maybe 1-3 years depending on usage, maintenance, and the materials). One thing I like about the Infinity 010-060
is in addition to being a very clean cutting blade, it can also be used for a lot of tasks on a TS...clean rips to ~ 5/4", fine crosscuts, and is an excellent plywood blade (on sale for $60).