I have a Janome Jem and have really been happy with it. Weighs 12 lbs.

I have this machine, learned how to quilt on it! It's very low priced, easy to use, since you already have a Brother
Machine this little machine would be perfect!

I love my Featherweights!! Best machine to take along. Keep looking...you will find one. I just found my fourth at a garage sale on Long Island for $25!!! My first three were gifts from mom, my mother in law and a dear friend.

Janome Platinum 12 pounds!
 

I have a small Janome Platinum gem that only weighs 12 pounds, it is wonderful for retreats and sew days. My 'at home' machine is also a Janome (6600) which I love, also. So nice that all the accessories (bobbins, feet, etc) are interchangeable between my two machines.

I would get another Brother so that a quarter inch on it would probably be a quarter inch on your home machine. A lot of projects that I do on my travel machine have to be finished on the travel machine because I can't get the same quarter inch.

at home I use my Pfaffs, away I use one of my 221 featherweights, but if I start on a 221 away I finish on it as to keep the same seam. I love my 221's down to just four now, one black with ex. table one teal, royal blue, and one hot pink. What can I say? I LOVE color! When I go to my retreat I take two, 221"s, my craft tote, cutting matt, iron, and all too much stuff, along with cloths pillow, and a quilt for my bed, all fits in my smart car for two.

I have a Pfaff Passport 2.0 and also a 221 Singer featherweight that I use for classes and sewing groups.
Sharon in Texas

I have a few...

If I'm just going to be doing piecing, I'll usually bring either my Featherweight or my 301 (The FW's "big sister"), depending on which one hasn't been "exercised" recently. Both machines are also great for taking someplace where I don't know people yet, because they will often draw people over and help start conversations.
If I'm going to be doing any actual quilting or need a walking foot, (or don't feel like talking to people about old sewing machines that day!), I will usually bring my Janome 3160

I love old machines and sort of collect them, so sometimes I'll use a class or outing as an excuse to bring whatever newest addition to the family is along so I can get to know it better, but in those situations I usually bring one of my tried-and-true machines in my car, just in case the new guy has an issue I didn't know about. I clean and test them at home first, of course, but sometimes there are things that don't turn up until you've sewn on it for a bit and I'd hate to miss out on a class or gathering because of a machine failure when I have over twenty of them!

I think it was Rob that posted how to set the default setting on the Brother 420 so the needle is always in the center when the machine is turned on. I set mine and it has worked every time. No more having to remember to move the needle!!

I have a Bernina Bernette and I love her!! Just perfect for guild sewing nights and it does just a few stitches. Straight, zig zag, and a couple others. Can't beat it and she was only $200 I believe.