RL: I'm no expert, by a long shot, but I thought maybe another 1/2" on the rudder. Frankly it flys fine and I can hold it in knife edge with the stock rudder. There have just been a couple of times that I thought some more rudder would be good. Hard to quantify. The better pilots on here might have a different opinion. You could always build it stock and if you want more rudder later it would be easy enough to replace the rudder.
I'm using this motor: http://www.hobby-lobby.com/brushless-skatty.htm
HL seems to vary the price on this motor every week or so. I have seen the price go from $19.90 to $24.90 to $19.90 to $24.90 over the past several weeks. I bought 4 at $19.90 to use on my 10-12oz profile planes. It worked so well on those that I thought I would try it on the ~18oz Hiperbipe.
Brad: Vinnie Finn, owner of JustGoFly. Here's the JustGoFly website. A good selection of motors and their accessories and lots of useful information.
Here is the particular motor I was referring to. I bought if for use on a wing. Scroll down for direct drive and geared tables. http://www.justgofly.com/tech_450TH.htm
. I bought it with both the standard (high speed) bell and the lower speed bell (see the 450T page) to try swapping out for various props. I got mine in pusher configuration. You can also get them in a tractor (behind the firewall) setup with the shaft coming out the other way.
Here is what I think is the same motor at Balsapr in the tractor configuration:
This other motor looks like it would be good on the larger Hiperbipe dd 10x4.7. However, for $19 I'm pretty happy with the tiny little 400xt. http://www.justgofly.com/tech_450XT.htm
Notice JGF rates it at 18A/180Watts while BP rates it at 13A.