What type of sites are you trying to rank and for what projects you using this for.
I currently use Senuke X for micro niche sites and non difficult keywords, so it works great for link diversity. But depending on your projects some programs will be more usefull then others.
If the competition is very high, you would probrally need both, Senuke X and Xrumer combined make an all star duo, so since Xrumer is a one time fee try purchasing that, then maybe pay monthly for Senuke X,
The only problem with Senuke X right now is that it crashes ALOT, but its great because it has everything included, boomark,web 2.0,articles,forum profiles,rss,social network,press release, so for low comp keywords its really easy to rank for with a solid module.
Another option would be to purchase Senuke X then just outsource Xrumer for your Tier 2 and Tier 3 links. You can also just use scrapebox as an alternative for Tier 2 and Tier 3 link, But Xrumer and Senuke X are two totally different programs, so to really get the full SEO power you would need both.
And as other people said, Xrumer has a big learning curve to it, Senuke X is very easy to use.
You should ask: XRumer 7 & SEnukeX OR http://www.blackhatworld.com/blackhat-seo/buy-sell-trade/288596-venomseo-released-captcha-solving-search-engine-optimization-automation-tool-3-day-trial-risk-free.html