All I can say is: Try several. I've used Koflachs and am neutral on the subject of their fit—neither bad nor great. I'm more favorably disposed toward the Scarpa Inverno ($290; www.scarpa-us.com), an extremely good buy in a high-end plastic boot. Weight per pair is around six pounds. The fit is generally excellent, with sufficient flex to help keep shin bruising to a minimum. For me, at least. I can't say that's going to be the case for you, so try a pair on in a store and walk around for a while before buying, then wear them at home for an evening before heading out on a climb.
You don't say what you'll be using these for, so I have to ask: Are you sure you need plastics? Because these days there are a whole bunch of leather or mostly leather boots that work extremely well in the cold/wet conditions in which plastics excel, but offer greater comfort. Scarpa's Freney Pro ($279) is an excellent boot—fairly light and comfortable, yet capable of hard crampon work in cold conditions. So is Salomon's SM Expert ($250; www.salomonsports.com), which incidentally is available in women's sizing. I wore this boot—at just under five pounds per pair—up Mount Rainier last summer and was extremely impressed with it. So, unless you want a boot for winter mountaineering or expedition use, give leather a chance.
More boots and hikers reviewed in Outside's 2004 Buyer's Guide.