Thanks guys for your comments. Actually, with the balance issues - even though the .55AX isn't that much lighter than the 61FX, it is at least a little. This can only make it EASIER to balance I feel. Also, I'm not planning on doing any loops or vertical stuff with this aeroplane as that wouldn't be done in the real thing anyway. Given the propensity of this particular ARF to shed its wings if handled harshly, I feel there's another reason to treat it a little gently. I'm really just after a Sunday-flier that looks the part. I have the in-cowl muffler that will fit the .55AX with just one extra mounting hole drilled in the manifold so it will all fit within the cowl quite nicely. My only question really that remains unanswered is:-

Will the .55AX have sufficient power for scale flight? From what I'm hearing, the .61FX has more than enough power for the job and for scale flight needs to be throttled back anyway.... Normally, I'd just go for the most power I could fit under the cowl, but on this occasion I'm thinking more conservatively - definitely out of my league on that score!!!

Thanks again,
Greg