Your analog futabas are fine for this plane. Using the best digital servo in the world isnt going a make a noticeable difference in the way a Hanger 9 Twist flys. If you were flying something more like a fliton extra or even a funtana I would say digital is better but the twist is a washy fun fly plane capable of doing some 3D (yep, Ive flown one). With this style of plane precision isnt going to matter. If you want to purchase some digitals as an investment for later then sure go for it. I would buy the Hitech digitals b/c they are programable (IMO one of the biggest advantages of going digital). Which Hitech digitals??? If your not going to go far above a 1/4 scale then the 5645's will be just fine. If you plan on ever using them in something thats 33% or larger go with the 5945's. As mentioned you will need more battery b/c the digitals drink more juice. For this plane I would get some kind of 6 volt NiMH say about 1200 mAh should do you fine. Personally I fly 2200 mAh Li-ions with a regulator on all of my .40 sized planes because I HATE to charge!!!