Thanks All for the response.
The current status is:
1. The DC DC converter can only put out 10W at the moment and the controller chip overheat, the requirement is 16.5W. This partly due to the limitation of off-the-shelf transformer.
2. TI's official footprint for the differential to single-ended conversion amplifier is wrong, the part cannot be soldered, thus bandwidth testing has to wait.
A new revision is being made and waiting for delivery. The new revision uses bigger magnetics and discrete low Rdson transistors to reduce heat generation.
The DC DC conversion is isolated push-pull topology running at 1 MHz. I do not know what the noise performance will be, but they are marketed as low noise topology in linear tech's datasheet.
The bandwidth is not a major concern. TI has quite a portfolio of very high speed opamps. They perform pretty well in the past for me.
For dual slots plugins, my plan is to take two boards and you connect the output to you digital scope by X-Y mode.
If the project can get good traction, I can make a dual slot version to better serve the community. The dual slot version will be a single pcb with an even bigger DC DC converter (33W). Considering the dual slot audience is low speed output signal for both sampling and spectrum analyzer plugins, I could even include ADC and PC data acquisition, such that the addon board will be fully standalone. Of course, once I put fpga and adc on the board, it make sense to get the readout included. But that would be quite down the road. (I do have a existing board design that capable to readout >16bit signal at 2MS/s with working FPGA firmware).