Absolutely. It will solve many flow issues and provide maximum filtration. 55 gallon aka 4 foot long tank is the tipping point where I recommend a drilled tank with a sump. My recommendation would be to go to your LFS and to purchase a used reef ready setup. It will save you a fortune in costs.Not sure yet. Should I?
Petco has tanks that are perfect for sumps if you are still using a 55 I would personally use a sump of 20 long or 30 long. As for overflows you can use a hob overflow but it can be a gamble so it would be more convenient to drill the tank