Is a conventional interior drain tile system likely to silt up over time?
In my area conventional drain tile loops are used extensively. They often use "sleeved" pipe, which has the silt sock you mentioned. They generally work well, assuming that they're not crushed by concrete work or careless backfilling. 

If you have extremely smooth clay-like soil, silt may be a concern. The microscopic grains in clay can make their way through the sock over time. Otherwise, you won't see much silt at all after the first season or two. My sump water runs completely clear after heavy rains, as do most others I've witnessed. This is anecdotal information, of course, and your results may vary. 

In short, I wouldn't be concerned about using a sleeved "conventional" drain tile loop, assuming that you haven't heard horror stories from a bunch of folks in your immediate area.



I don't know of anyone who has needed more than one sump pump. If you find that yours is running more than say 10% of the time, it might be wise, but that's something you can evaluate later. It's really a matter of risk tolerance.