The tubes are probably fairly large, so I wouldn't assume that the flow restriction is going to be significant. It may very well be better for coolant flow than some heatercores.
It looks like a common AC evaporator. Got a link to it?
Otherwise, I wouldn't bet on good performance: you can do better with a heatercore. The heatercore performs better because the coolant flow is restricted, through an arrangement of zig-zagging brass plates, which puts the coolant in turbulence, improving heat dissipation. Straight tubes, like the unit above are usually made of straight (round) pipes.