The only advise I would give you is start looking for a home for them now. They grow very fast and it is harder to get rid of big fish than smaller fish. My eupterus grew from about 1.5in to 8in in less than a year.
IMO cyps aren't worth the hassle, especially with a tank that borders "too small" for them. 10 4" fish aren't going to be very comfortable and considering that they are very fragile fish, I wouldn't invest in them personally...i would say go for it my friend, sounds nice, just a reminder cyps are a flight risk so make sure all holes are plugged if not they will find that 2 inch hole and jump right out of it, hehehe, that 20gal community sounds sweet i have a 20gal with 3 rainbowfish in it, later buddy..