Here are a few thoughts on reasons to change a riser.
- To create a longer (smoother) or shorter (faster) bow
- To change the bow hand position. Difficult to justify a ?500 riser for the grip though.
- To change the physical weight of the bow. Some people find it difficult to hold a lump of aluminium up or have shoulder problems and switch to carbon risers.
- Wanting a multipurpose bow. i.e. a riser that can accommodate static weights for barebow and stabilisers for olympic
recurve.
- Wanting better limb alignment / tiller adjustment options.
There may be other reasons too but imho if you're not looking to achieve any of the above then probably no reason to change the riser. The money would probably be better spent on stabilisers or a custom grip (Jaegar).