For the record I don't believe lower order batting is insignificant, just don't rate it as highly as others do and it comes into play for my No. 8 only, after that it's the best three bowlers available period. For me it's all about balance, a No. 8 who can handle a bat, a batsman who is a competent fifth bowler and at least two batsmen/bowlers who are great slip fielders are all equally important to a side.
So for me personally a player who is brilliant in at least two of those roles and test standard in the third is the rarer talent and so Kallis, Sobers, Chappell and Hammond (some would include Botham and Miller and Mitchell and Simpson aren't too far off either) are priceless additions to any team and brings even greater value. Incidentally there are only 4 players with 3000 runs, 200 wickets and 100 catches and they would be Sobers, Kallis, Botham and surprising to some Warne.
So the 5th bowler and No. 8 batsman doesn't have to be necessarily exceptional, just a bowler who can bat a bit to extend an innings when needed and hang around with a top order batsman; and a top order batsman who wouldn't release pressure and consistently nip out the odd wicket or break a partnership when he is brought on to bowl. Because in the end you have to make the team on your primary skill and the rest is just a bonus.
Just my two cents worth.