SG,
I have two Sportsters in .22 (actually I have 4, but more in a moment)...
I got them for my kids and my wife and I to "just plink" and they do that wonderfully well. So far we have primarily been shooting the Colibri no powder rounds because we haven't gone to an official range, just to a friend's property where he has about 20 yds where we can shoot.
These guns with the Colibris are very accurate and very quite. (Even quieter than my wife's Crosman Mk1 CO2 pistol) We have shot a few rounds of Rem hollowpoints at water filled gallon jugs, but mostly the quieter ones.
As for your question about whether .22LR Sportster is good for plinking, my answer is a resounding YES!
So now for the "more in a moment" I have four, two are still unfired, new in box. If you decide to get a whole new rifle instead of replacement barrel, let me know, I'm open to sell/trade one or both of them.
We really don't need 4 Sportsters. My kids are only with me part of the summer each year, and 2 NEFs will do us all just fine... besides my wife likes shooting her Henry lever and I, my Marlin 39 Mountie.
Cheers
Kerry