Downtown redevelopers are rooting for Yehuda Amar, the investor who recently completed work on two Bank Street properties and is marketing his penthouse unit at 147 Bank St. for $2,300 a month. “I love it. I want him to succeed,” said Frank McLaughlin, who owns 55 rental units in 19 buildings in the city, 16 of them downtown. “If he can get that, that’s good for me and the upscale, New York-style loft apartments that I have downtown.” “I think Yehuda will do well in those spaces,” said Mel Foti, another downtown redeveloper, who is finishing work on his own building at 18-20 Bank St., opposite the former H. Marcus & Co. clothing shop, that he intends to rent at higher price points. “I live downtown, and I know what I pay in rent, and what my neighbors pay, and I think there is definitely a market for higher-end apartments downtown,” said Foti, who also is planning redevelopment of the Barrows Building at 253 State St., which he owns with a partner.