the allrounder issue is also going to be a very subjective one when it comes to all time XIs, personally i only see their use as being thereas a bowling allrounder. this isn't to put down batting allrounders, and they very well may get some overs if they're in the team but there really aren't any genuine allrounders who have the statistics to back them up to bat top 6 and bowl as a genuine frontline bowler.
for that you would need to look at guys like miller, procter, imran, gregory. all great allrounders and useful to any team but in an all time team who is going to pick them in their top 6 when they didn't even average over 40? most would want their all time top 6 to average 50+ for consistency reasons.
personally for me sobers makes an all time team purely on his batting so really this issue with his bowling doesn't make a change with him for me when picking an all time team. similarly if i was to pick kallis it would be as a batsman.
i'd rather have my top 6 as genuine batsman, then gilchrist would be my keeper, then my bowlers. you already have a strong batting line up there so don't need allrounders but can still easily pick guys like imran, hadlee and even miller without losing much in the bowling but adding a lot to the batting whereas if you were to pick them as a top 6 batsman you'd be losing probably more from the batting.
i honestly doubt sobers was a horrible bowler otherwise he wouldn't be considered the best allrounder ever and by a lot of people the best cricketer ever. i haven't seen his bowling but from people i know who have they all say he was a very good bowler. as for kallis, he isn't an all time great bowler either but having seen him bowl is can be very effective, he's actually quite decent so i'd have no trouble wanting him to bowl a few overs even in an all time XI.