The sliding miter table is a good idea. On mine, the slider is a little more than 1/32' higher than the rest of the table. Often, that doesn't pose a problem, but it can make the cut a touch off square (vertically). For detail work, that is a pain. Making a crosscut sled will eliminate that problem. Overall I like it. Fine-tuning your Ryobi BT3000/BT3100/BT3K table saw When properly aligned, the BT3K cuts as precisely as the finest cabinet saw. The saw's manual does a very good job of laying out alignment procedures that get it 'close enough.' Dual - Dual Slot Miter Tables - RYOBI BT3000. With a Dual Slot Miter Table mounted on each side of the main saw table along with the accessory table it provides a full 35' wide table, 36' from the left side of the Sliding Miter Table to the left side of the Rip Fence.

Ryobi Bt3000 Table Saw Specs

While I dream of the day that I get to buy a more serious tablesaw, I currently own a Ryobi BT3000. While it has its limitations, it has been very useful over the last six years. Of course, it cannot really take advantage of a lot of jigs and such that rely on the miter slots in standard tablesaws.
I have heard of a miter slot attachment put out by Ryobi. Here is a picture of a left and right one installed.

Ryobi Bt3000 Sliding Miter Table

Ryobi Model Bt3000 Table Saw

Ryobi Miter Slot Table 4060310