This is where I'd point you to my data warehouse idea... http://thwack.solarwinds.com/ideas/2637
Since the historical data will be used for reporting and statistical analysis, it is best to move it off of the production database.
Hopefully we can get Solarwinds to take this idea and run with it.
In the meantime, if you don't have performance issues, then I wouldn't be too concerned but I would keep an eye on things.
Indeed, we are experiencing the growing pains already; many of our detailed stats tables are in excess of 200 million rows, and the maintenance job runs for two days; rarely completing reorgs and updates against the larger tables.
The database performance guide is of little help once you get past the basics and have the disk and general hardware requirements in check.
I think its screaming at you..."I need a data warehouse !!!"