Good morning D,
You're starting off the shopping/comparing process at a great time and asking the right questions! That goes a loooong way to finding yourself in a boat that will keep you safe, comfortable and happy with your choice in the long term.
It will not come as much of a surprise to you that I find a lot of answers in your question.
First off, in your current ride, you're not comfortable and that has you seriously looking for an upgrade so let's confine the discussion to the two Duckworth models you mentioned.
It's interesting that by implication you consider the 26 Offshore to not be as trailerable as the Duckworth Navigator 235. The Navigator has a dry weight of 2600lbs and while the Offshore has a dry weight of 5300lbs, both hulls are easily handled by a dual axle trailer and 3/4 ton pickup.
I run a Weldcraft 280 Cuddy King which I launch and recover by myself frequently.
What the Offshore offers is a softer ride, heated cabin and higher eye-height over the water that will, ultimately add to the days you can use your boat which lengthens your season.
On the other hand, the 235 Navigator is a significant upgrade from your current hull, will be less costly to tow/operate than the Offshore and if your "two-footitis" progresses as mine has, the Navigator will hold it's value quite well if you ultimately decide to take the Offshore plunge.
To the choice of the glass boats, IMHO.. In this region the disadvantages of fiberglass hulls with regard to increased weight and maintenance.
Some boaters prefer the look and feel of a fiberglass hull and that's great! Beauty is in the eye of the beholder but do not be swayed by claims that 'glass boats just "ride softer" than aluminum hulls.
It does not matter to the water what the hull material
is. The issue is hull shape
Since the advent of CAD (Computer Aided Design) aluminum cutting and fabrication programs in the 1980's and the decades of developments in the interim, pound for pound, aluminum hulls are stronger and softer riding than their composite counterparts