I have sat staring blankly at the wall for a while now and really can't think of anything that could be called a weak point on the inter 20! its a really good boat - congratulations!

One trick that I did learn was for when the rudders start to come up a fraction at speed, giving a bit of weather helm. the first instinct is to change or try and tighten the springs. But it is the pairs of rollers that are wearing. If you wrap some insulation tape around the top one to thicken it up a bit, it does the trick.