I normally use a thin kerf 40 tooth Forrest WW II on my saw, and I am quite happy with the results generally. I bought a BORG .125 kerf Tenryu combination blade last year to cut spline slots for miter joints on small boxes, and found that it doesn't leave a flat bottom in the slot (I've learned how to use small flat file as a result).
I'd like to be able to cut deeper slots (along edges and in in end grain) on the saw, and I have heard that a decent .125 kerf rip blade is a good choice for this. Is this a good idea, and if so, are there some decent (<$75) blades that you'd suggest? I suppose I'd also use it to for rip cuts on either end of the slot cutting process, but as I mentioned I don't feel a need for a high-end rip blade as a general matter.