Well, yes and no. I mean, the bittering IBUs will be correct, but the flavor will be affected in some beers.
for example, if you're making a beer that is bold and citrusy (like an American IPA) and you use all German hops, it'll taste "weird".
What I do when I order by the pound is think of my favorite beer styles and recipes and order the hops I'll use in them. So, for Belgians maybe I'd buy Styrian goldings. For English ales, East Kent Goldings. For american APAs/IPAs, cascades.
Since you like some malty beers with little hops flavor, you could try a bittering hop like magnum, since that will work with all of your favorites for bittering. Even a stout can be bittered with magnum, since it's only added at bittering. But an IPA can utitilize magnum for bittering, too, and then the cascades (or centennial, or amarillo, etc) can be used for flavor and aroma hops.
So, my suggestions:
1. Magnum (bittering for most styles, as it's pretty neutral)
2. Cascade or Amarillo or Centennial (for IPAs/APAs/Ambers/American Stouts)
3. East Kent Goldings (Irish beers, English beers, stouts)
4. Tettnanger, or hallertauer or saaz (German beers, some malty ales, "clean" hops flavor)
5. Another one of my #2 suggestions, depending on what you like.