Beautiful Simon, I am so inspired. Thank you dear brother.
Now the answer follows :
My dear sister, you have asked why the special placement of OM after "Hari". But for **all** other Deities, why "OM" is before there name.
am I correct my dear Lotus in understanding your question ? , if i am the answer is that always the OM represents the manifestation with respect to the absolute, who is "Hari" dear Lotus.
OM is Turiya and Hari is Turiya Teetha Brahma-Purusha.
Om is the all creative force. The Brahman. and Hari is "Brahma Purusha" and OM is himself, it is in him this OM, called as Pranava, the all creative creation force present.
He himself is Brahman, and he Radiates Brahma Jyothi, which great yogis realize in the highest state of Nirvikalpa Samadhi after turiya.
and this is OM.
and after realizing this, the ultimate is the Turiya-Teetha and that is the eternal permanent existence and that is service to Hari.
just know that he himself is OM. Pranava is nothing other than him.
what simon wanted to say is "Hari OM Tat Sat Chit-Ananda", This is complete form, and it is the only mantra Where OM is Preceded By Deity. Meaning Hari is not Deity, but he himself is the source of OM.
meaning Hari is the Pranava OM, who is tat , sat and chit and who is ananda ( bliss ).
So, Hari Om = Hari is OM.
But in case of other deities, OM is them, meaning they are manifested from OM.
This also explains why all other deities meditate on OM and Krishna, but Hari meditates only on himself. This is also confirmed by Sri Adi Shankara-Charya , Lord Brahma and Lord Shiva themselves and many many more.
I can give you slokas, but the post will get very very long. :)
Lord Bless,
-- Deito
Harirnama Harirnama Harirnama Kevalam.