"Because I'm a very efficient packer the bag was HEAVY."

That sentence Dianne and your belief that it is true, are why your saying they need wheels might be called 'nonsense on stilts'. It shows a very one sided concept of what 'efficient packer' means.

Efficient could be about how much 'stuff' someone can squeeze into a bag. Obviously, that is how you are defining it. But what if 'efficient packing' is about how lightweight your bag is when packed? For me an 'efficient packer' is someone who goes on the OP's 3 week trip or 3 month trip and only packs 5kg./12 lbs. including the weight of the pack itself. I wouldn't have said your comment was nonsense on stilts but I would have said that your bag was too heavy. Simple as that. Can you see the difference in perspective? From my perspective it wasn't that your bag was the problem, it was what you packed that was the problem.

First, the OP says they want to go 'lightweight'. The problem is everyone has a different definition of what 'lightweight' means. For some it means they pack less than 25 lbs. while others take it to mean under 15 lbs. and still others, anything under 50 lbs. If it meant under 15 lbs. to you Dianne, your pack would not be too heavy and you would not be suggesting wheels are necessary.

There are several ways to go about deciding what bag to buy. As a lightweight (5kg) traveller 7sloane I would suggest the following.

First decide what you absolutely need to take. Efficient lightweight packing is not about packing a sweater etc. 'just in case'. But if you decide you absolutely need to pack your hair dryer then so be it. Just be as ruthless as you can about need vs. nice to have. Once you have a list of all your 'needs', here is the KEY.

Go out and find the lightest weight example that you can, of each item on your list. You can buy a 4 lb. pack such as your Motherlode example is or you can buy an Osprey Porter 46 (just an example) that weighs 2.4 lbs. That is a difference of 1.6 lbs!!! Both have the same dimensions of 22x14x9. The Tom Bihn Aeronaut is popular and also the same dimensions but it weighs 3 lbs. 1oz. which is more than half a pound heavier than the Osprey still and so for me a non-starter. I want the lightest bag I can find that is still good quality and robust. In fact the Osprey and the Aeronaut are made from the exact same material and the Osprey is arguably more comfortable to carry on your back. So where is the justification for the weight difference? For the size being discussed here I would say that 3lbs. is the maximum weight acceptable for the bag itself. NO 22x14x9 bag with wheels is going to come in at that weight. In fact, Dianne's Maxlight 2 spinner weighs a whopping 7.2 lbs. That's why it needs wheels.

You can buy a packable nylon rainjacket that weights 14 ozs. (nearly a pound) or one that weighs 7 oz. (under a half pound). Both do the job equally well. You can pack 6 pair of socks and underwear or you can pack 3 pair. There's a saying for that. 'One to wear, one to wash and one to spare.' No one NEEDS more than 3 pair of socks or underwear. As Iwildernova suggests, you just use soap and wash them in the sink at night. Three pair of socks and 3 pair of underwear weigh around a pound total. Six pair weigh double that obviously. That's a pound added that isn't needed.

A bar of Ivory soap will wash your body, your hair, your dishes and your dog if you want it to. Biodegradable soaps made for camping such as 'Campsuds' will do the same thing. As it is concentrated, only a few drops are needed and a 2 oz. bottle will easily last a month.

So the point is, if you want to travel lightweight, you have to think differently. Find the lowest weight example of each item you need to take; look for multi-use items that eliminate having to pack multiple items; be ruthless about what you need to take. I can guarantee anyone that if you do not know the weight of every single item you pack, you are carrying more weight than you need to.

Once you have what you will take assembled 7sloane, then it is time to determine what size bag you need. Not put the cart before the horse. Does it really make sense to buy a bag first and then see if your 'stuff' will fit into it? What if it doesn't fit or the bag is half empty?

Put all your stuff in a plastic bag, compress it and use tape to hold it compressed temporarily in a rough cube shape. Measure length x width x height and that will give you a measurement in cubic inches. Once you have that you know what size to buy and are ready to start looking for a good lightweight bag of that size.

In case anyone wonders, I'm a guy and manage with under 5kg. in my bag when I walk on board the plane. My wife manages on just a shade less in weight. But she doesn't pack 5 pair of shoes or a little black dress, just in case.