Difference between Nallo and Nammatj... Nammatj is stronger, as already suggested, but the Nallo is still "4 season" and is still properly strong. Bear in mind that the Nammatj is used off-the-shelf for unsupported polar expeditions and you can see the level of bombproofing is going to exceed that needed for most cycle touring... But you also get a bit more sitting up space in the Nammatj because it doesn't taper to the rear, there is better venting (a full rear vent) and IIRC the vents have mesh to keep bugs out of the porches in summer.
However, I personally prefer the Kaitum, made from the same materials as the Nallo but with more inner space and a porch at each end (of course you don't get something for nothing, so it weighs and costs more).

Here's ours on the dunes of Benbecula, where it shrugged off a gale (though it was a bit noisy inside).
For a 3-season Hille tunnel the Anjan (or GT extended version) would be the one, based on the Nallo but in lighter fabrics and with the fly not extending all the way to the ground and mesh panels in the inner for better venting when it's hot. There's the Rogen if you really want freestanding, and/or two porches. The MSR mentioned is quite a bit cheaper and still a very good tent, but is more of a faff to pitch. The Hubba Hubba is enough for two, but only just... You do save weight by cutting the size though The "HP" models are lighter and stronger, but of course more expensive. When out touring with the family my wife and I use a Kaitum 3 (when Hilleberg say big enough for 2 or 3 they actually mean it, btw) and the kids go in a Hubba Hubba HP next door, with the Kaitum big enough for everyone to come in for meals if it's chucking it down.
I'd agree that free-standing is over-rated. The Hubba Hubba (and our Tarra bunker-class tent) are free-standing but it's frankly a
meh for cycle touring. Handy for marginal pitches, yes, but they have to be pretty marginal indeed for it to really matter. We've pitched our Kaitum on 1" thick turf over a shingle beach where the pegs were no use, but still managed fine by using rock piles as anchors.
I'd also agree that crawling around in a tent is a Really Good Idea before you shell out for it. If that's not possible pitch indoors first to test it, so you can send it back. If that's not possible, test pitch outside on a big plastic sheet and use a different set of tent pegs, again so it can be sent back unblemished if it isn't quite what you had in mind.
Pete.
Often seen riding a bike around Dundee...