I run Letro when I bulk, but I typically run a bit more than 500mg of Test a week. Of course there is going to be a Test to Letro ratio that works for all dosages, but if you're not pushing at least a gram of Test a week.. then there's better options.
I'd go with aromasin at 12.5mg daily. There is also an over the counter AI called Arimistane that is great for water retention. I honestly think it is more of a diuretic than AI. 100mg daily will have you pissing out gallons of water at night.