first of all i was flat wrong about "impossible to compare".
it appears that the eagle 245 ds is like the lowrance x4 pro in many respects.

Eagle 245 & Lowrance X4 pro:  1500W peak to peak output, 60 & 120 deg cones, 1000' max depth.
Lowrance X4: 800W output, 60 deg cone, 600' max depth.

So:  600' is good enough, 120 deg cone is nice but not necessary, 1500W is almost double 800W power output. what this translates to in battery consumption is prob most important to me. i really don't know nor can i find battery life ratings on these, so most likely it's best to take the safer route and go with the X4 (that is if someone can shed some light on battery life).