Hi Elsaurio, loving the focus on getting the Squats updated.
I'm hoping to get some playtests soon - just want to start by summarising what the changes are that have been discussed so far.
Cyclops:
CC4+ changed to CC5+
6x Doomstorm Missiles lose IF
Colossus:
CC4+ changed to CC5+
No Spotter rule, so Doomsday Cannon loses IF
Leviathan:
Two different directions. Either:
1) CC4+ changes to CC5+
No Spotter rule, so Doomsday Cannon loses IF
25pt decrease to 350pt, or something similar to make it a more attractive option compared to Rhinos/Termites
Or:
2) Replace with the Cadian version.
As comparison, the Cadian Leviathan has 2 less Void Shields and oddly for an Assault Transport it doesn't have Thick Rear Armour. Also missing the EA(+1) Bolter Array.
It does have 120cm Doomsday, 45cm Lascannons and the Fighting Deck which potentially gives it a bunch more FF and shooting.
It's basically priced at 325pts.
Personally I think taking the Cadian version would lead to confusion (different ranges on Doomsday in the Squat list, similar Squat WE with/without TRA). I'd prefer trying to tweak our version (though the fighting deck does seem tempting

).
Land Train:
I've always thought there are 2 viable builds with the old Land Train - the one you mention with a Rad Bomb plus 1-3 Berzerker Carts which sits on the Blitz and sustains every turn. Or 4x Berzerker which for 400pts gives you a DC6, 4Void shield WE with good shooting and a bunch of 4+ Assault dice (14 if you have at least one enemy in FF and CC) but is slow.
Part of me doesn't want to give up that flexibility, but I do like the look of the assault themed Land Train.
In particular, the bump to 20cm, finding a use for every cart and adding some AA to the Train.
I did some sample builds to see if I can break the Train:
4x Demolition Mortar: 500pts
DC6 4+RA, 4 Void Shields, 60cm 3BP MW, 75cm 2x AP4/AT4, 60cm 12x AP5/AT4 Disrupt, Assault - 10x FF4+.
4x Rad Bomb: 600pts
DC6 4+RA, 4 Void Shields, 60cm 3BP MW, 75cm 2x AP4/AT4, 60cm 4x MW2+ TK(D3), Assault - 10x FF4+ (4 of which are TK(D3)) or 10x CC5?+ (4 of which are TK(D3))
I think we'd probably have to tone down some of the Carts a little else my opponents refuse to play me... haha
So, maybe for Rad bomb - make it Slow Firing or MW3+ TK(D3). Remove the EA+1 CC TK(D3) - you probably don't want to drop that fatboy too close to your Train.
Not sure about the others?
Berzerker Cart seems about right, though i'd probably cap the CC bonus at 3+ or 4+. I can't really see myself taking more than one anyway (for the AA and bump to CC4+) when the other carts are now better.
Maybe the others can be fixed by simply limiting the number in each train to 0-1 or 0-2 for each type?