Hi again deepsoup.
I see your problem.
The main difference between Tomiki and other styles, Shodokan being Tomiki, is that Tomiki aikidoka learn aikido as a sport. What I mean is... you learn the moves and movement in the
context of a sport.
The form used is, one person attacking the other with a knife to the centre of the chest, I think. In kamae, the chest is half protected, which is no good to Tomiki/Shodokan because you must present the target for it to be attacked, so you're original 'stance' is (yonho)Shizentai.
Other forms of aikido also present a target, sometimes, (as I'm sure you know, I'm not trying to give a sermon
) it's just that in Tomiki they have more concentration on the chest. So I suppose, in a way, Tomiki/Shodokan is harder, because the attack is mostly directed at your centre.
Of course, you have to remember that I'm a beginner, and this is only what I think.
When practicing aikido should your posture be:
a) shizentai
b) kamae
c) depends
d) doesn't matter
e) won't matter later on