I like the Wasp boss head for replaceable blade heads.They fly great,and are sharp heads.You can get replacement blades for these as well at any good archery shop,and are not very expensive as well.
I might give the Montec G5 head a try this year as well,heard alot of good things about them.Simple is the word,easy to resharpen if need be and never have to replace the heads,only thing about these is a little more expensive.Come in a pack of three,yet the wasp boss heads come in a pack of 6 for about the same price.
If your looking for a good,accurate,forgiving head,then give the montecs a try.
If your looking for a good accurate,forgiving head with the option of replaceable blades then give the Wasp Boss head a try.
Either one,you wont be dissapointed