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Had a prop strike on an 1800 hour high-time engine (IO-360A1A). Turns out it was an omen. The internals were looking terrible (most certainly from long before the strike, with camshaft that shed bits of metal into the cylinders. Looked horrid) and I am told the prop governor was not long for this world. So, that is how I am rationizling my mistake that lead to the strike. So, the price of an IO-390 A3A6 was only slightly more than a IO-360. Therefore, I am going to go with that. Lycoming seems motivated to get more of us Mooney drivers to consider the swap. When you go with IO-390, you have to buy a new prop-governor anyway, so that is $$ I'd have had to pay anyway if I went with that. Now, with a high-time old beater motor in my E (3-blade top prop conversion, 201 winshield and some gap seals [tail, dorsal, flap, LASAR cowl enclosure, smooth belly]), I was getting a TAS of 150-151kts. my main question is, what can I expect with a 2 blade vs a 3 blade. I read that MAPA PIREP a few years ago of the guy in the upper midwest who was dissatisfied, but noted that the experiments were not carried out with much scientific rigor (i.e., he usually was at X thousand feet before he got to the edge of the lake, but now, with the IO-390 he was only Y thousand feet). I didn't know what to make of that. The Glastar Sportsman article featuring a head-to-head comparo of the 360 vs 390 seems more valid, and shows significant performance increases. The approved Hartzell prop is a blended airfoil design, which I can't say would change performance much based on what I read on the Van's Airforce site of a guy that had a long conversation with the Hartzell engineers, but certainly would look cool. Anyway, your thoughts would be appreciated on which number of blades to buy. I have to decide which prop to order soon. FYI: I fly out of a 5000ft paved runway in the SE at 600ft MSL and do a lot of long X-crty trips. Monroy tanks installed too. bdjohn