Yep, I was in this boat a year or so ago when the 310 came out. I was coming from Uniden and trying out the GRE.
Basically, the GRE has memory that is not sorted by banks. It's global. So you can scan trunk TGIDs in the same group as a conventional system. You can't do this with Uniden.
An example would be montioring all LE activities in a single group. So you could have CONV State and Trunked Police in the same grouping of channels -- and then scan this "bank" only.
For trunking systems, the GRE scanners store the SITE info into a specific memory which can be recalled later. When you want to scan a specific TGID then you just specific the site(s). So you can have TGIDs from multiple systems in the same bank.
You can also monitoring just the trunking channel and then you'll 'search' for new TGIDs.
Personally, it was hard for me to change over to the GRE-way of thinking. I can see that it might be beneficial in some aspects but the programming is much easier on the Undien, imho. The GRE has some odd quirks about its style. Also it's hard to beat the small portable aspect of the 346/396 versus the GRE scanners. Yes they have the 800 now but it doesn't have a keypad.
If you're comfortable with the Uniden method, then I would stick with it.
PS. I only had the 310 for a couple of months so my above recollection was all from memory. If something is not accurate above, I'm sure the GRE owners will chime in.