I cannot give you any information about the specific sound that would result from the capsule switch. But here are some things to consider:
* Make sure the Manley capsule is of similar acoustic construction as the Røde's. I am not familiar with either of these, whether they are single or double backplate types. But if they differ, you may need to electronically compensate for different high-frequency response (difficult to do on a chipped processor like the Røde's)
* As far as physical fit: measure the inside diameter of your Røde capsule mount. It needs to be big enough to accommodate the outer diameter of the Manley capsule.
* Evaluate the financial implications before you buy the Manley capsule: Frankensteins by definition have a lower customer demand, so selling this mic at a reasonable price or at least without too much of a financial loss may be hard.