Agree with a lot of that. I'm currently evaluting fitting a wooden floor to our 340 as we only ever keep it fully inflated - this would help to stiffen up the floor, push the keel down more and stop the dreaded rythmic 'wallowing' you get underfoot when planing if you don't get the weight distribution just right. Had a Yam 380 with Yam 15hp out on the river a couple of weeks back (a much heavier - about 110kg outfit compared to around 56kg for the Zodiac 340/Tohatsu) but with a wooden floor and more substantial keel - the difference in the turn was fantastic, I won't say it bit the water like a RIB but it made the Zodiac seem like a lilo...
Having said all that I'm still searching for a Y Class so that will be a lot more solid and I proably won't bother with mods to the Zodiac but keep it lightweight and easy to use as it is.
This Avon was another beauty and bargain that went through eBay this week and would have been a brilliant buy, superbly built and in lovely order - a real classic looker too:
eBay - The UK's Online Marketplace