I have a light gray crispaire suit from Chan. Makes a great suit imo. I also have stuff made of the 11.5 oz, 4-ply finmeresco and the 9/10oz, 2-ply Minnis fresco. All three are great imo, but the heavyweight Smiths (4 ply) is probably not really a summer suit. More spring/fall. Being 4 ply though, it's probably the most durable--certainly feels that way and it's worn well over the past few years of intense use.
For a real summer suit, I don't think you really can go wrong with the lightweight Smiths (9.5), crispaire (10 oz?) or either lightweight Minnis (8/9 oz or 9/10). Of these, the coolest wearing is probably the high-twist Minnis, followed by the 2-ply Minnis in a tie with crispaire. The Smiths may be as cool as these last two, but I don't have any experience w/ it other than feeling swatches, and from that limited exp., its weave was certainly smoother/denser than Minnis 9/10 and, I think, a little denser than Crispaire. It may be the most durable of them though, because it's three ply and, acc. to Arnold, woven of superior (longer-staple, I think) woolen fibers than the other two.
Other than these characteristics, color is important, and I wouldn't worry if that was your deciding factor.