I just wrote a really long post describing our challenge with this, but then somehow hit the back button in my browser, and lost the post. Sorry, can't repeat it.
Summary version:
Current implementation has sandrider only for melee, not guardsmen.
Its problematic to change this, and to remove suspensors because of:
a) AI issues
b) Unit roles (we don't want too many roles filled by too many units)
c) Empty tech-tree (we don't want too many techs empty/useless for Fremen)
d) Balance (we want Fremen in deserts to be vulnerable to thopters and hornets)
We've thought about this before, and ideally we'd like Fremen to be even more different, but its hard to implement.
Yet another new player here, and like many I seem to have been tempted by the Fremen out of the gate. Anyway, I'm having the same problem with infantry and defending my settlements. The core of the problem is, when I tech to be able to build Infantry, who cannot enter desert on foot,
I can no longer build soldiers, who can. Fremen don't get scout thopters as an early transport, which means cities on other rock formations (and my starting rock pad was quite small) at best can only be defended by fremen scouts until they can build their own defenders. Makes escorting settlers against barbarian threats a wee bit difficult as well, if only strength 1 units are available for the duty.
As a fix, I'd be happy with soldiers not going obsolete so quickly. If I could move a soldier with my settler, then even upgrade it to infantry in the new city if necessary, that would be fine.
Anyway, loving it so far. I'm probably going to abandon this game and start a new one, since expansion is so stifled currently, but that's okay. Haven't noticed anything glaringly in need of change otherwise. Sandworms seem rather tame with their slow movement, but that could easily be a factor of playing the Fremen. And I agree that early vultures from goody huts seem very powerful, though I did not use mine very aggressively (or effectively: I like to scout the map too much), from reading others' comments.
Edit: A minor bug I came across starting my new game: When regenerating the map (Arrakis type, haven't tried archipelago), all the spice disappears.
Another question: what happens with the Tlielaxu religion's founding if there are more than one player of that faction? Will both factions get the religion, with one being the "founder"? With only 9 factions, this is quite likely for default settings on maps larger than "large."