It's pretty clear that MPs have a lot of bonuses going for them - easier to program, they sync, wider flow (WPs have a more narrow beam relative to MPs), and have a much sleeker profile. Really, they're better in almost every way, except for one massive downside - cost!!! Well, that, and depending on what you're looking for the upsides may not be that spectacular either - WPs create plenty of randomized flow and waves, if that's all you're looking for, save the money. Unless you really like that low profile of an MP (I understand that completely by the way, were trying to make beautiful tanks after all!)
If you have a nano, be cautious purchasing a WP 25... You will also need a lower voltage power adapter than has been provided with it ($15 - 20). Despite down-volting mine, the only way I could make it work in my 30g cube was by pointing it across the back of the tank more or less directly at the rock..... I still get neat looking waves though, lol. Every other direction kicked up a huge sandstorm and threw frag plugs all over the place.... Nothing was happy in the tank, lol!
As for not being able to point an MP... I never felt the need to? They work best pointed at a flat surface across from them anyhow. Well, actually, they work best pointed at a flat surface with another MP on the opposite pane....