I think you'd regret putting in a drop-in sink. One of the big pluses for having Silestone is being able to have an under mount sink & being able to wipe things straight into the sink & not have the ledge to catch everything. The difficulty in ever replacing the sink & how soon would that be - really ? I can't see (if you get a good quality sink) ever having to replace it. But anyway, way, way way down the road , if you ever do have to replace it, the difficulty in that could be addressed now. Check to see how your Silestone fabricator install an under mount sink. If he drills holes in the bottom & uses sink clips, or does he use an undermount bracket system. All you would have to do & probably have a plumber do this anyway, is break the seal, then unscrew the undermount brackets or the clips & pull it down.
The more difficulty comes with your cabinet, see if you can get your sink base to have a mullion attached to one of the doors instead of a center stile between the doors. The stile will be part of the face frame & make it really awkward to remove that sink one day, also harder for the plumber or whoever to get in there to hook everything up. If you have a mullion attached to one door that opens up access to the whole interior of that cabinet.

Good Luck

Here is a link that might be useful: granite countertops

Replacing an undermount sink is no big issue on 3cm material or materials with no sub top. If you will have a sub-top (normally a wooden underlayment like plywood), just make sure that there is enough play around the sink so that the sink lip does not get pinched between the solid surface and the wood. It would then simply be a matter of disconnecting the plumbing, undoing the sink clips and breaking the silicone seal.

That being said: You will probably want to replace your counter tops before needing to replace your sink anyway, so the replacement issue really should not be that worrisome.

Undermount sinks are easier to clean around and to me, just looks way sleeker than a drop-in model.

My 0.02

I love the look of undermount sinks. I guess I failed to mention that my DH is not the most graceful or careful creature. My sink at my old house, which was new, ended up with numerous scratches within months of him moving in.
I just want to be practical.

Gail428...why don't you have to clean the "ick off the sink edge" if you have a drop-in sink? With our old drop-in sink crumbs, etc. were always getting caught along the rim of the sink and we had to use fingernails or other to clean around it. With our undermount sinks, it's so easy to keep clean now!

If you're getting a SS sink, then allow the scratches to create a patina...over time they blend to form a consistent-looking appearance so scratches no longer "show". If you're getting a coated cast iron sink, then you may have a point...

I do know that our old SS sink was 13 years old when we demolished the kitchen and it was still going strong...yes, we had a patina of scratches on the bottom, but b/c there was that patina, they were not noticeable.

Where do you think the most scratches will be? If on the bottom, then consider getting a sink grid to protect the sink bottom if you don't want the patina. A grid also keeps dishes raised off the bottom of the sink so they don't sit in dirty water and you can rinse things down the drain w/o the dishes in the sink getting in the way or blocking the drain. Ticor sinks (at GalaxyToolSupply.com) come with a custom-fit grid for each bowl of their sinks (grids are included in the price of the sink).

Here are a couple of threads that discuss some of these issues:

http://ths.gardenweb.com/forums/load/kitchbath/msg0516542828229.html

http://ths.gardenweb.com/forums/load/kitchbath/msg051226339151.html

Sink Undermount Reveal Options [To help w/decision on over/undermount]

There are pros & cons for each type of reveal:

• Positive Reveal. The sink shows; granite cutout is slightly larger than sink

• Pros: Easier to clean b/c you can see the gunk and can easily wipe it off (it only gets nasty if you leave it there)

Cons: Silicone (caulk?) is visible, but if they use clear you won't see it when it dries
Negative Reveal. The granite overhangs the sink; granite cutout is slightly smaller than the sink

• Pros: You cannot see the gunk buildup or silicone

Cons:

• You cannot see the gunk to clean it.

• Dirty water/food can splash up & under where you cannot see to clean it. It's difficult to see underneath w/o leaning way over & into the sink.

• Dishes/glasses have been known to break b/c when you lift them out near the edge of the sink the dish hits the stone counter & can break (or, if the dish wins, the counter could chip...but I'm not sure how likely that is).

Zero Reveal or Flush. Sink & granite are flush or even; the granite cutout & sink are the same size

• Pros:

  • Easier to clean b/c you can see the gunk

  • No platform over or under for the gunk to collect

Cons:

• More difficult to do perfectly

• Silicone is visible, but if they use clear you won't see it when it dries

I wondered the same question, then asked myself the more relevant one: WHY would one need to replace a sink? It's not like it can go wrong. It's essentially a large metal bucket with a drain. What's to go wrong? You might need to replace the drain fitting, but I realised the likelihood of ever needing to replace a sink was minimal to nil.

oops - I meant my favorite thing is I got rid of the drop in sink and now have an undermount!!