Good question.
I agree that based on what I've read, most will say that the sump at the bottom will be more ideal. However, I am concerned about the following :-
1. 2 foot tank with sump at bottom means chiller have to sit outside.
2. If I get the reefer 170 with sump at the bottom, I will need to then get the following separately - skimmer, light, pump. I have very limited knowledge to get one that is good enough that will not burst the bank account.
I did toy with the idea of custom build a tank to do the above, but most place work out the sum to be around the price of getting the Max 170 with questionable parts (e.g. lights, skimmer, etc).
I am hoping that this tank, if done successfully can last me about 3 years? If the result is good, I think the family will be more acceptable of a bigger tank? lol.