The poly count over all is less important than the texture count.
And normal maps can only go so far.
And how many of these are in any one mission?
I'd say, keep the existing working item. Make a duplicate where the "ripples" are modeled in. We'll see how much it increases poly count during smoothing and conversion and which impacts performance the most. If it's negligible, we'll put in the "ripple" version.
Of course, I'm only speaking as someone who can barely manage to import a DAE, size and smooth it, export it and have it turn into a POF in Blender, so I realize that this is something I can't really do and I appreciate the amount of skill and work it takes to do this, and I think it would look really sexy. And I think the engine can afford it, but it would be better to have one that isn't to fall back on, just in case.