It's been about a year and a half ago when I ran a 20XD/300X with different props. I ran a 28 Performer, 28ET, 30 ET, 30 Mercury cleaver and 29 SRX DAH while testing. The 3 blade Performer was the fastest prop and the 2nd fastest was the 28 ET...the Performer was about 1-1.5 MPH faster on topend and was quicker on holshot and midrange. The Performer had not been worked at all, but if you buy one it may need to be adjusted a tad to get it just right. I ran the prop before it had a name and was VERY impressed with it...it really doesn't look like it would run all that good with it's thick blades and big diameter, but it does. I haven't had a chance to run the 4 blade yet, but there are a few people around here that love them.
Paul