1. My experience I have found is that Xrumer can be used sparingly on your money site if you already have a couple of thousand backlinks and an aged site with good content rankings anyway
2. BUT there is a a small risk that a forum you piss off will start making nasty noises and report you. That is what worries me. Now I have no idea if Google actually listens to these reports but I really don't want to throw away 2 years work on the off chance!
3. ALSO xrumer links have a high decay rate especially as far as I can see in first three months so you need to have additional automated programs working in the background to at least not have negative link velocity.
4. The google boys I am sure are wise enough to attach a higher value to a balanced portfolio of backlinks from press releases, articles, blogs the whole 9 yards than just one source. 5,000 profile links I think might just stand out if you have 5001 links in total.
4. FINALLY people who say you cannot grow links really fast or that links have to be context relevant or that new sites cannot rate high on Google are WRONG. What happens when there is a disaster like the BP oil spill, the Iceland volcanic eruption or worse some rubbish new Boy band is launched Suddenly really obscure site plus lots of new ones spring up with 000s of backlings. Google has to figure into its algorithm a backdoor so they get high SERPS positions immediately (and are 100% not sandboxed) or it is out of business.
So the morale is think how the pattern of links would grow for a boy band or whatever and replicate it! By the way press releases, forum comments and blog comments would by my bet on what Google really focus on. Anyone noticed how forums are really prominently featured on Google now