I'm in the planning phases of a 20L and am thinking that a rimless tank would be bad ass. the thickness and the length of the glass is a bit of a concern for me though. I'd only be pulling the top rim off and could make an acrylic eurobrace if it will make a solid bond to the glass.

has anyone have a long term run with a rimless 20 long?

It will not make a solid bond to glass, not enough to brace it. Glass to Glass or Acrylic to Acrylic when it comes to bracing.

Before I got my 34G Solana I did the exact same thing you're planning on doing. Bought a 20 gallon from Petsmart and took off both the top & bottom trim for a poor man's version of an ADA tank. Had that thing running for a little over a year before I got my current tank.

Used a putty knife to help take off the trims. Then used Goo Gone & a box cutter knife blade to clean the rest of the silicone off the top rim & bottom rim of the tank.

Never did put on a euro-brace...I did all of this on a 20H...should be more stable on a 20L since it's shallower (less chance for tank to bow at the sides...IMO). Good luck!

how do tank builders like AGE bond glass to acrylic? We have a local reefer in our club with a 600g tank that is acrylic with a starphire front. I believe another guy also has an acrylic/glass tank. Both have a PVC bottom.

My Nano, good to hear!

I pulled the top & bottom rims off my 10 gallon Aqueon (formerly AGA) tank today. Getting the rims off was fairly easy, but getting off all the silicone residue... I must have been scraping at the tank for an hour with a razor blade and some rubbing alcohol (the alcohol really helps loosen the silicone residue, makes a big difference. Goo Gone helps a little bit, but not as much as brand new set of sharp razor blades and a bottle of rubbing alcohol). But still, I'm really glad I did it and would do it again in a heartbeat. It's amazing how different the feel is, it really inspires you to do amazing aquascapes and really helps provide a new "dimension". As for the safety, I have absolutely no idea. Hopefully it works, but I'm going to wet test it outside for a few days first. Also, I found that hacksaws, believe it or not, really help a lot. It made it SO easy to get the corners off, just have to be careful about hitting the glass (I was in a hurry and did nick it a few times, but there just small dimples, not really noticeable)
Good luck, and sorry I couldn't be of more help.