Your rear rack has the stigma of low price - it's already paid for.
;-)
Racks are handy things. Rear racks can hold a lot. The problem with weighting down the rear has been discussed ad nauseum with the rando crowd. It significantly affects the handling of the bike (tail wagging the dog), especially if you like to stand and pedal occassionally on uphills. Rear wheels already hold ~60% of the bike's weight, and dishing the wheel makes if weaker than the front, so why add more weight to it?
Go find pictures of randonneuring rides. Search images for
Bicycle Quarterly's un-meeting, or just @
rhm or @n_lerner's flicker sites (
Rudi and
Neal, respectively), you'll find almost all of them are riding with a handlebar bag. This puts the weight over the front wheel, which alleviates all of the issues above.
It can get expensive, however. You can easily spend $4-500 on a front rack and handlebar bag. You can also get by on the cheap with a bag that attaches to the handlebars. On a "taller" bike like yours, that might put some weight a bit higher than optimum, a small rack that sits right above the tire is more optimal.
Or just ride with your rear rack and a small rack top bag. It all depends on how much you want/need to carry.