From 2007.igem.org

Suggestion 1.

Merit:
The repressor R1 can be inserted after constructing the other part.

Suggestion 2.

Merit:
A ribosome binding site here is easily exchangeable; therefore, the expression level can be modulated without changing the promoter and regulators.

Suggestion 3.

Merit:
Promoters can be easily exchanged, and the expression level can be modulated at promoter level.

Suggestion 4.

Merit:
The precursor of this part was constructed for the functional check of BioBrick parts and available;
therefore, this construction can be done in much shorter time.