Are gu10 48 led bulbs (daywhite) brighter than at least a 35w halogen gu10 bulbs? ?

To answer that you need to know the lumen output of the 48 led bulb compared to a 35W halogen bulb.
A 50W halogen bulb is in the region of 1000 lumens and I’d guess a 35W GU10 halogen to be in the 600 – 700 lumen region.
I’d expect you would need an LED bulb to be rated around 6W to get near to a 35W halogen bulb brightness (i.e. 700 or so lumens). Daywhite LEDs are generally brighter than warm white for a given wattage, so that is working in your favour. I hope you find the 48 LED bulb bright enough for your application.
Not sure about returns policies in the US but in the UK we have minimum of 7 days to send goods back if they are not opened – and a sometimes a re-stocking charge if you unpacked the item and actually used it. Merchants can refuse to take back an item if its been used. Advise you just try 1 if you can before unpacking a bunch of lights.
I’m setting up an online low energy lighting store in the UK and may do trial LED lighting packs so customers can buy & try.
Try to get a figure in lumens for any LED lamps you buy and compare with halogen. You should be able to get specs online. You can then see how close the LED bulb will be in brightness. You also need to check whether you want spotlight or wide angle lights.