I like the feel of the Purple mattresses better too, but you need to try before you buy. Tempur's bases are some of the the best in the industry, especially with the lumbar support. Ergomotion is the manufacturer, and they do a great job. More on reddit.com

Unfortunately, there’s no straightforward way to make a queen adjustable base fit a king mattress. A king is 16" wider than a queen (same length) so you’d need to add 8" on each side which is a big challenge structurally. We haven’t seen a reliable retrofit kit that can convert a queen adjustable into a king. If you’re very handy and up for a DIY project, you might be able to remove the decking and rebuild a wider platform using the existing motors. But that would involve a lot of time, effort, and uncertainty especially if the motors and frame on a queen aren’t rated for the weight of a king mattress and the new decking. Your best bet might be to look for a no-frills king adjustable base. Some models out there skip extras like massage or lighting and just lift the head and foot. They tend to be more affordable and a lot less hassle than trying to reengineer a queen base and might cost less buying everything to rebuild it. Also, depending on your area, check out local Facebook groups or other platforms like Buy Nothing or similar ones. In our small community, we have a members-only group where people post things for free like kids’ old bikes, old furniture, and sometimes even adjustable bases. It’s hit or miss and obviously harder in big cities, but definitely worth checking out. Hope that helps! More on reddit.com

I keep looking at them, but then wonder if it wouldn't be irritating to be stuck having only the positions the adjustable frame adjusts to. I'm dithering about whether or not I shouldn't just keep using a foam bed wedge for my head/shoulders and foam feet wedge (forget what it's called) on my box springs so that I can move them around to wherever I want on any given night or nap. I'd like to hear from people who currently use adjustable bed frames about whether or not they get aggravated at only having the various positions that are built into that frame, or if those positions are always what you need? More on reddit.com

Well… your mattress is definitely gonna hang off of a full size base. And since a queen is 5” taller it’s not gonna bend in the same places as it would on a proper size. That’s my first concern for you doing that More on reddit.com