Here is a delema.

I have a 2100 zr9000 al carbon bike, 63 cm. I would like to build up someday a madone 5.2 or 5.9 frame. I want to someday use the 2100 for crits due to the greater durability of al in a crash and little weight difference and as a trainer and use the madone for group rides and centuries, etc. (Maybe some road racing).

The delema...
I was thinking in a few months around my birthday after I do my 3 centuries in 3 months to get a few upgraded parts for my bike. Here is what I want to add.

A new Bontrager race XXX lite fork (Carbon 110, al steerer, nice fork)
Bontrager race XXX lite stem, 120 mm (10 mm shorter)
Bontrager race x lite handlebar, full carbon

I already have race xxx lite seat post (330 mm)
race lite selle san marco saddle
race x lite areo wheelset

I will one day get a frame for the madone build up, probably next season. I have also thought of going cdale which is a very real choice that I will have to make. The question is whether to buy the parts now, enjoy them for 6 months to a year and then swap them onto the full carbon frame and go back to the stock parts or keep the parts and buy them when I buy the frame?

The reason I want to do a frame build up is I am an unusual size and I want to buy the parts I know will fit me and the bike. I am also thinking of campy so that would require a trek one deal which I do not want to do. To add to the question the 2100 will be used as my crit bike mainly due to the fact that I am afraid of what will happen to a 1800 dollar frame + 1300 dollar wheels in the event of a typical high speed crit crash. My 2100 is built for durability making it the choice abit 1 to 1.5 pounds heavier for crits and training.

What do you all think?