Gurbani has repeatedly condemned practices that some may consider OK for their private or even public worship. a good example is the 33 Swaiyye of Guru Gobind Singh Ji in which Guru Ji has condemned nearly all known practices claimed to bring one closer to God.

I will draw your attention to one paurhi from the Tawprasad Swaiyye that we read daily. the paurhi is the last one and it goes:

kahuu laih pahan pooj dhariyo sir kahuu laih ling gare latkaiyo, 
kahuu lakhio har awachee disha meh kahuu pashah ko sees niwaiyo, 
kou butaan ko poojat hai pas kou mirtaan ko poojan dhaiyoh, 
KOORH KIRIYA URJIO SABH HEE JAG SREE BHAGWAAN KO BHED NA PAIYOH.

A rough translation would be:

why are you worshiping this stone idol and why are you wearing this image of the lingam around your neck?
why do you say that God resides in a particular direction and why do you bow your head towards the west?
some worship idols, some worship animals, and some worship the dead, 
the whole world is engrossed in false actions (rituals, worship methods, etc.) and no one is able to know God.

The above is a rough translation and I may be wrong.

If the translation is right, then Guru Ji has strictly given us guidance that these ways adopted by the world are wrong. a person who wants to know the secret of knowing God must come to theGuru who will guide him to receive the grace of God. thus while these practices of doing his meditation upside down, lighting diwaas and doing aarti of creation (not the creator because no one can possibly do that-Guru Nanak) standing up or sitting down, etc. are wrong in gurmat and therefore not to be practiced by sikhs, we cannot stop others from doing or believing in them. these are the 'bipran ki reet' thatGuru Ji has warned us about. thus if a sikh wants to practise them and insist that they are alright for sikhs and even encourages doing them in the sangat, then he needs a refresher course in sikhi and gurmat.

Is it alright for a sikh to do this things in the confines of his home in private? Guru Ji's instructions are clear. no, they have no value in gurmat. they will lead you away from God. "sree bhagwan ko bhed na paiyoh". "karam dharam pakhand jo dheeseh tin jam jagati looteh".

What about 'freedom of practice'? yes one can practice what one likes. God has given all of us our own will and choice. A Muslim can worship as he pleases, and so can a Hindu, Christian, Jaini, Buddhist, etc. but they cannot say that they are followers of gurmat. and neither can anyone else whose religious/spiritual practices are as condemned by gurmat.

Sikhi is a very tolerant faith. it allows you to practise what you want and you will get what God decides to give you. but if you are a follower of gurmat, then my dear brother, there is ONLY ONE WAY, the gurmat way. and in gurmat the Guru Panth has full authority to interpret what the gurmat way is. NO ONE ELSE HAS THAT AUTHORITY.

To answer the question about aarti ofGuru Granth Sahib, the panth has said NO in deference to the wishes ofGuru Nanak as recorded in raag Dhanasari Mahala Pehla "gagan meh thaal.......". we must remember that the spirit ofGuru Nanak is sitting on the throne when we are doing aarti in the gurdwara. and i am sureGuru Ji must be thinking of "KOORH KIRIYA URJIO.........".

Enough said. not intended to hurt anyone's feelings.