Yes, it's worth it.
I, too, sleep on my side (actually both side, back, toss 'n turn). Won't trade my NeoAir for any other pad (except other NeoAirs!). Just got an Xtherm for cold weather, but my Xlite works fine in most temps I've been in.
The weight, for comfort and warmth it provides, can't be matched by anything else I've used.
Unfortunately, I just sold my original Large or you'd be in luck! Check out Gear Swap for good deals.