You really can't go wrong either way, to be honest. What you will need to do is consider is what your provider actually provides (ie; do they provide all true high definition programming or are signals compressed? Almost all companies compress at least some programming).
As with all other applications, your results may vary, although only slightly. Individual component choice will come into play and will affect the final result greatly. What helps is to make a list and keep track of what you change and/or modify. This can be something as simple as upgrading a cable. Keep diligent records and be sure to note any favorable or unfavorable results.