Lack of switchers via holding a button is a step backwards, otherwise, the Edge is the superior product.
The logic for the lack of switchers doesn't connect for me. If it's because Edge is aiming to be mass marketed and taking away this feature means it would less likely be viewed as a cheating device; most or many gaming mice have on board memory type switching already. Not cheating.
If the rationale is to encourage future customers to possibly choose the more expensive XIM3; this is unlikely, since most new customers will want PS3 support. Current XIM3 owners would be more inclined to upgrade to a XIM Edge since it's universally better if switchers was enabled.