I own both. 4" bull barrel Ruger 22/45 and 6" Trailside. Right now if I had to give up one it would probably be the Trailside by a very narrow margin. I had no mag problems, they were with the early models from waht I've read. I did have a failure to lock the slide back after the 7th magazine. Sent it back to SIG and they replaced the slide stop and gave me an extra mag and had it back a week after they received it. Great customer service!
In my opinion:
22/45
May be a little heavy, but is that bad?
Reassembly is a challenge until you get it down - FOLLOW ALL of the instructions - but you know this by now.
Rock solid.
Grips are OK for me, but can't be replaced.
Accurate.
Stock trigger is OK.
Red dot sights can be left on for disassembly.
Magazines are cheap.
Trailside
Almost too light, but thas can be remedied by adding weights.
Assembly/disassembly is simple.
Seems solid after the repair, but I need a few thousand rounds to tell for sure.
I have the el cheapo standard grips, but they can be replaced.
Just as accurate - maybe moreso after I shoot it some more.
Stock trigger is real good.
Red dot sights have to be removed for disassembly. (The internals don't seem to have much to gunk up and you can use a bore snake to clean the barrel.)
Magazines are expensive (especially for plastic).
Hope this helps. Personally, I'd keep them both.