A good lightweight 3/4 size machine is a Japanese clone of the Singer 99K-10. They are made from aluminum and are the same as the 99s but don't weigh any more than the FWs. They have more room under the arch, stronger motors and share the same feet and accessories. The only supply difference is they use Class 66 bobbins and are top loading. Many folks don't like the top loading part. Me ... I prefer it.
These machines can be seen badged as Bantams or just named as my SEWMOR 303 is:
[ATTACH=CONFIG]488984[/ATTACH]
Notice the feather through the logo.
These are what I'd go for if I wanted a 3/4 sized carry around machine. Oh ... right, I already have one
Joe