Usage of -ю ending for Instrumental case?

Question

I checked Was -ю ending in instrumental mandatory in Pushkin's times? but I wonder how about using this ending today for adjectives, pronouns, etc.?

1. What style or color does this give a text?
2. Will it be hardly noticed or is it striking?
3. Would it be strange to switch between -ой / ей and -ою / -ею?

Answer 1

It will look like a speech from 19th century, possibly like a citation from some classical work. Yes, it will be noticed and sound strange.

Answer 2

While I agree to most extend with all answers proovided, I still insist that in colloquial speech not always but pretty often this does not sounds outdated. It is just something quick you don't even notice. Pretty much like in colloquial English it is acceptable to ignore some of grammar rules.

Check out, for instance, this phrases:

• Что вот с тобой не так? Со мною вcё нормально.
• Друзья, мне кажется с едою что-то не так.

"-й" version is de-facto more acceptable and "-ю" is definitely getting obsolete, but still does not sound too strange in many cases.

Answer 3

I think it can also be used to achieve the effect of sounding colloquial and possibly less educated, at least that is what I get out of Vysotskiy's usage in the Song About The High Jumper:

Но я лучше выпью зелье с отравою 
И над собой что-нибудь сделаю,
Но свою неправую правую 
Я не сменю на правую левую.

Normally we would say с отравой

This might be a challenge for non-advanced students of Russian, so I'll give my translation as well:

I would rather drink a poisoned potion,
And I would do something to myself,
But my right (leg) which is in the wrong,
I will not change to the left one which is (considered) correct