I would create a Chunk, which holds the template-code for all different templates
named 'baseTemplate'
<body class="page page-template-default header_2 fixed_slider">
<!-- Header -->
[[$_Header]]
<!-- End Header -->
<div class="top_wrapper">
[[$[[+pageHeader]]]]
<section id="content" class="page-dynamic_template-home sequentialchildren container ">
[[$[[+contentChunk]]]]
</section>
</div>
</body>
Then have different Templates like that:
[[$baseTemplate?
&pageHeader=`_HomeCarusel`
&contentChunk=`_HomeCarouselText`
]]
[[$baseTemplate?
&pageHeader=`_PageHeader`
&contentChunk=``
]]
Better to have different Templates, than using many if-statements.
If you still want to use IF-statements, call them cached and make sure the code inside isn't processed, if not necessary, so it would look like that.
[[[[If?
&subject=`[[*id]]`
&operator=`EQ`
&operand=`1`
&then=`$_HomeCarousel`
&else=`$_PageHeader`
]]]]
See also
http://modx.com/blog/2012/09/14/tags-as-the-result-or-how-conditionals-are-like-mosquitoes/