Mavericks GM hasn't been too good for my 2011 MacBook Pro. This machine has only 4 GB RAM, and it shows. It's swapping noticeably more than before, and overall everything feels less snappy than on Mountain Lion.
On the other hand, the battery life is definitely better. It's not really worth the performance hit, though...
Late 2010 MBA using the old Mavericks GM - 13A598 - is fine. No different than 10.8 at all. 4 GB RAM on a C2D. I really don't think I would have even noticed the difference had I not had to run the installer.
Interesting, the RAM compression should actually increase performance. Well I would highly recommend an SSD for you, with 4gb RAM my Macbook Air flies, and it's all thanks to the SSD.
I second the SSD upgrade. I regularly use three different MacBook Pros -- two with standard hard drives and one with an SSD. The SSD makes a world of difference. It feels like a new machine. I never have to wait for anything, not even Photoshop or Word. With the standard hard drives I always get spinning pinwheels, 5 minute boots, etc. In my opinion, even the 2013 MBPs are unbearably slow with standard hard drives.
I got a couple of 2TB WD Greens for $85 apiece and a ZyXEL NSA221 two-bay NAS (some ARM chip running what I think is Debian but I've never bothered to look) for $120. I think that one's discontinued now, though.
You need to define what you mean by "big enough" and "affordable", considering there are now 1TB SSD for ~$500, which I personally consider both "big enough" and "affordable enough"
That's plenty big enough, but kind of pricey compared to $65 for a 1TB hard drive. Try to get either of those capacities in a laptop (I take pictures when I travel), and the gap gets even bigger.
On the other hand, the battery life is definitely better. It's not really worth the performance hit, though...