I have never clicked the upgrade request button, but I am Platinum. My concern is let’s say I have the resort I really want and put in request to go 2 to a 3 bedroom unit. Looking above it looks like your Resorts changed... So what if your nice resort gets upgraded to a larger room in a less than stellar location.
Using example above say you have HGVC Tuscany 1 bedroom, but get upgraded to blue tree 2 bedroom. This would be a downgrade IMHO.
You can't receive a bigger unit at another resort.
You can request for a unit upgrade at the same resort and/or to change resort for the same unit size as you booked (you select the resorts you would accept). Also, if you have booked a Saturday check-in as example, you can request for another check-in day.
From RCI:
When you book your Exchange vacation, just let us know you’re interested in
a unit upgrade or resort change. Within two weeks of check-in,
if one of the resorts you’ve specified, or a bigger unit at your confirmed resort becomes available, we’ll change your reservation and provide you with the details.