I have not ridden a 24 scout, but the 28 is horrible riding boat and very wet, and from other owner's I have heard similar instances. They are light boats, scout utilizes some newer age technologies, which can be a good thing, but they have also had issues over the years with laminate problems and having problems with fiberglass adhering to core, which is a bad situation, the core becomes powder inside and has 0 strength putting a lot of stress on the fiberglass that was not designed to be that way. I am not sure of what years this effected but they had a run of about a year with issues like this. When we looked at moving up Scout was on our top 5 list, but after hearing from owner's and looking more into them, we eliminated them. their fit and finish is nice on the outside, overall finish work is ok. Grady builds a great boat and if cared for correctly will last longer then you and I will, granted they have some issues too, but typically they are caused by owner negligence or lack of knowledge and care. As far as amenities, the 23 Grady is very well laid out for a 23. The scout has a smaller cockpit, no walkaround making it harder to get forward if you anchor or even when docking. Personally I think the dash on the scout is horrible, little room for electronics and they will either have to be out in the open or suspetible to glare. The scout does put you closer to the engine which I perfer over a bracket, but both are not too big of an issue. The side gunnels on the scout are neat and give you lots of storage, but take away from a LOT of cockpit space in the end, and on a 23-24' boat ther eis little to no need to have all of that space taken up. The cabin on the scout is nicer, but scout concentrates more room on the cabin, so unless you will overnight a lot and put fishing or lounging in the cockpit second, this on a 24' boat is a down side, you want an even spacing in helm, cabin and cockpit, on the scout they put more emphasis on cabin then cockpit. The 23' Grady is a solid boat and rides like a 25' boat, the scout 24' will ride like a 22' boat, there is no comparison in how the 2 will ride. The scout will be more efficient because it is lighter and rides like a smaller boat with a narrower beam, but you will also notive the difference when seas kick up, or even in a chop, weight can be a good thing in a boat, going lighter isn't always desired.
As you mentioned above, trailer is something to look into, but a 23' with that wide beam can be trailered, you will either need a permit for it or need to go online and notify your states authorities of your route for approval. Some states are more lax about it and do not fully enforce this law either, depends on your location and how far you will need to really travel, but being aware of the law in your state is something of importance.
As mentioned by other posters, reason the 24 scout rocked more was due to its light weight, the lighter you get the more rool action, typically a narrow beam boat would roll less then a wide beam boat, but this also has to do with deadrise, a variable deadrise will rock less then a straight v boat. If weight is located higher in the boat or the boat is made lighter, it will rock a bit more for its style boat. Adding the weight in the gunnels from the storage and fish box makes the boat act like a pendulum and will give it more momentum to rock more then a typical boat without those storage areas outboard. Also, having a box on one side that might not be filled all the time and gear on the other always being there throws off the boats stability a bit as well, it will rarely ever be equalized which is perfered. As far as ride, in a chop, a widder boat with more deadrise is best, if the boats have the same deadrise, the wider boat will still ride better, but burn a little more fuel doing so, in a beam seas a narrower boat is perfered, but on a 23-24' boat the difference will be minimal in the overall picture of the ride.
As far as offshore race boats, most are stepped or straight v boats or have little change in deadrise, so they are hard to compare, they ride well because they have a deep v for slicing waves, narrow beam to add efficiency and speed, and being narrow allows weight to be cut out. If you set that boat on the drift...yikes.
As far as the price and what you get, the scout will not hold resale as well, basis for the newer boat being in the same price range, this does not mean scout is a bad boat, but when you factor in customer service, longevity, and brand name, there are a handful of brands that top scout. As far as which suits your needs better, that is a personal decision, and you need to see what will give you the features you are seeking. The age of the hull is negligant, hulls last far longer then we do if cared for, so take that out of the picture, assuming both are in fairly decent shape. The engines are a big factor, the scout may have a better engine being newer, unless the 23 is repowered. When you look at it this way, this shows you that after the cost of the newer engine, the scout hull itself is worth little compared to the Grady's, looks on the outside sometimes mask the reality of the situation. I would highly advise a sea trial beforwe buying, even if you need to put money down you might not get back, in the grand scheme of things it is important to do so so that you do not get stuck with something you will not be happy with. Unfortunatley being a grady forum it is hard to get a perfect answer here, but coming from someone who works in the industry designing boats and someone who just went through a boat purchase a few years ago, there is little comparison between the 2 in overall value for your buck, with that being said, not always is the best bang for your buck the best fit for everyone out there.