Unicode in the equations: pros and cons

Is there any pros and cons for using of Unicode (and vice versa) in LaTeX equations?

Consider two examples:

\lim_{h→0}∫_{x_0}^{x_0 + h}\frac{f(t)}{h} = f(x_0)

x_0 ⇔ ∀ 𝜀 > 0, ∃ 𝛿 > 0,(|x-x_0| < 𝛿 ⇒ |f(x)-f(x_0)| < 𝜀)

And without Unicode:

\lim\limits_{h \to 0}\int\limits_{x_0}^{x_0+h}\frac{f(t)}{h}=f(x_0)

x_0 \Leftrightarrow \forall\epsilon > 0, \exists\delta>0,(|x-x_0|<\delta \Rightarrow |f(x)-f(x_0)|<\epsilon)

With latest XeLaTeX the result is the same, so!, what's better?

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See some discussion here Is there a way to use unicode-math in a more limited fashion and also some of the discussion in this recent chat session: Why use LaTeX instead of Word. –  Alan Munn Dec 16 '12 at 20:35
Probably ε (U+03B5, GREEK SMALL LETTER EPSILON) should really be 𝜀 (U+1D700, MATHEMATICAL ITALIC SMALL EPSILON). –  egreg Dec 16 '12 at 20:40
I'm pretty sure this would raise portability issues beside the obnoxiousness of a (virtual) unicode keyboard... something Word tries hard to emulate with the effect of giving me the creeps... –  Count Zero Dec 16 '12 at 20:41
Sorry for the question, but how do you input unicode characters fast? Do you look for it in a table? This is not fast, I think. If not, which is the usual method used? –  Manuel Dec 17 '12 at 14:03
@Manuel: I'm using XCompose in Linux with this config. –  m0nhawk Dec 17 '12 at 15:28