Hi
I own both machines and only detect wet sand to knee deep with both machines, as a preference to dry sand detecting or any other for that matter.
Disclaimer:
I have owned the Excal II for just under 3 months and E-Trac for around 18 months, I have been detecting for 30 years with many different brands.
I think your question has more to do with stability and depth on the sea shore as opposed to versatility of use.
My observations are these:
The E-Trac is ergonomically far superior, one can swing it for hours without aches, the Excal was designed for under water use and is balanced for that purpose.
The E-trac has programable discrimination, excellent for those who want to avoid a proliferation of a particular unwanted target, the Excal has dial discrimination up which can be frustrating, as it usually remains at 1 (lowest) to allow of gold items.
The E-Trac tends to get jumpy with water motion when the sensitivity is high, and tends to have slightly less penetration than on hard sand.
The Excal performs this task better, and is more stable in the surf, loves rings and finds smaller (good) items deeper than the E-trac.
My suggestion is to go the straight shaft and or hip mount an Excal for this style of detecting, in saying this, I prefer the performance of the E-trac, but the Excal is better overall in these conditions.
Hope this helps
Cheers
Bazza