Supported symbols is >
{% if TestValue > '5' %}Is Greater Than 5{% else %}Is Less Than Or Equal To 5{% endif %}
Supported symbols is >=
{% if TestValue >= '5' %}Is Greater Than Or Equal To 5{% else %}Is Less Than 5{% endif %}
If the input value is not an integer, this will NOT error, but will evaluate as false
So, given the above examples, if the value is Not-A-Number then then else condition will output/execute
If the value being checked is an integer (for example if you have used the length filter) then the conditional value should also be an integer.
{% if PropertyGroup|length > 1 %}More Than 1 Instances Of Group{% else %}1 Or Less Instances Of Group{% endif %}