Also SSD drive prices have falling drastically recently. So replacing with a larger one could be done quite cheaply now I would think.

Yes it is true that SSDs have a limited number of read/write cycles per cell. But with latest OS providing TRIM features for SSD drives which distributes the data around the drives more evenly to stop overwriting individual cells so often they are a lot longer lasting than originally thought. The specs for a new drive now states:

"250GB drive: 100TB Total Bytes Written (TBW), equal to 54GB per day for 5 years"