Nothing wrong with n+1.
Can't understand why people imagine they need carbon fibre anything ... unless it's to compensate for aluminium being such a crap material to make frames out of. Of course, if the lycra clad boys in your 'bunch' are going to laugh at you for not riding full carbon, and you actually care that they'll laugh, you probably do need carbon (you can assume that I have a difficult relationship with some lycra warriors, not all but a certain smug subset that are becoming increasingly common here).
If you want a lighter, better bike, build it or get it built or buy it already built out of better quality steel. Yes, it'll cost you money but cheap ally and cheap carbon is both heavy and rubbish anyway.
You'll save more real world weight in the components (which don't need to be carbon either) and you'll save the most real world weight by eating and exercising properly.
Of course, if emotionally you will feel most fullfilled by starting with a carbon or ally/carbon frame, go for it, that's what building bikes is really all about. Function is only a part of that satisfaction.
I still get my most satisfaction out of riding my old Europa - an eighties roadie made out of the normal cro-molly tubing of the day (ie, not super multi-butted tubing made of unobtanium steel, she's probably not even butted) with relaxed tubing and all the scars that thirty years of use can provide. Dunno why. Might be our time together. Might be something in the way she rides. Might be incipient insanity on my part. Might be because after many changes and upgrades and downgrades and regrades I've finally got her working in a manner that is perfect for me.