I made the decision to buy some KR trays as I'd heard many good things about them. I also decided to buy trays, rather than another GW case, as I doubt I'd ever be taking more than one army with me out at a time - trays can fit in a cupboard, or a box.
I decided to go for the following set up:
I purchased two 40 unit infantry trays, and one 'Pick 'n' Pluck' Cavalry tray. These fit in a GW case no problem, replacing the standard 3 infantry trays. The infantry trays can also squeeze up to 50 in each, but I wasn't confident that the more cramped trays would accomodate spears and the like, so opted for 40 to a tray, which is still +4 more than GW. The suggestion was that the cavalry tray would fit 24 Warhammer cavalry units. How did it do for LotR?
Round bases are always harder to transport and store, and so I was interested to see just how much I would have to 'pluck' out to fit them in - and how fewer units I could fit in. GW trays aren't ideal for 40mm round based cavalry - a good 80% will probably sit okay after removing excess foam, but the height is an issue. I've found any unit with arms or weapons that stick out to the side instead of straight forward can pose a problem - my mounted Arwen's sword arm came off from the pressure of GW foam trays.
As you can see, I've removed a good amount of foam to fit in The Undying - his staff makes it awkward to fit him in. Here's a reference shot.
The tray is pretty deep all things considered. I'd say you'd fit 24 cavalry in there, as long as they were thinnish, like Warg Riders. Galadhrim Knights or Dol Amroth might have a harder time and require more space. If a model is longer, you can take an extra segment out (see the warg rider with longer spear), and still be able to fit the same amount in. My current plan is to use the rest of the space in the same way as the current space for upright cavalry - the three larger spaces will do fine for the odd awkward model.
Overall I'd heartily recommend investing in some trays - they only set me back £15 and are well worth it. One last thing I'll add is that the trays have a great sturdy quality whilst also being soft - stacked up, they stand strong and grip together and to surfaces, and on the inside they're softer than GW so will have less chance for pressure breakages or scratches.
