Mine's the Sprint one. I assume yours is as well. And it's set to on-demand. But the same issues that led me to dropping Dolphin HD on my Evo are all there on the SGT. It's slow to load pages completely and worst of all, if you press on a link as it's loading, it won't respond until the page completely loads, at which point after the page is formatted (which itself is slow), the area where I pressed the link is now a different link and it goes somewhere else. So I go back, but Dolphin has already dumped that page so I have to reload it for the link. It's just so frustratingly slow that I had to ditch Dolphin. It did not do this before froyo -- I loved Dolphin on 2.1. I don't have the patience for it now.
Oh, and the other frustrating issue with Dolphin is that it frequently does not give me feedback that it's doing anything after pressing link. I have no idea if it's loading the link or if it's just hanging.
I'm not against it, and I use tabs all the time on my desktop browser, but it's just not how I browse on my phone. I will say this -- Miren gives you the option of opening the tab in front or behind. Dolphin forces you to pick either or as a default. So if you like opening tabs, Miren might actually be better.
And like I said, the ability to really jump back to the previous page and not have to reload means I'm not forced to open tabs. Your method is the only way to make Dolphin even usable.