Bill, it sounds like you're really enjoying your amp! 

I recently got my OTS set up (with Klein-ulator) and getting the tones I like (lately my head has been into Larry and Robben tones.  I'm running NOS US-made Philips 6L6WGBs (basically 5881s), and I agree that they seem more "toneful" than the bigger 6L6GCs.  Maybe not quite as powerful attack on notes (?) but seem "fatter"(?)  More "liquid"(?).  More "bloom"(?).  Maybe that's the same as "splatty", I don't know...hard to describe how musical sounds feel with words.  To quote Sheryl Crow, "if it makes you feel good, it can't be that bad".   

For preamp I'm using a '60s Mullard for V1, NOS Telefunkens for the other two tubes.  The amp really seems to like all kinds of guitars...so far tried with ES-339, Les Paul, Suhr Strat (sounds somewhat like Larry's Valley Arts), and a St.Blues Mississippi Bluesmaster with Burstbucker 5s (sounds better than I thought it would).