Regarding the OP, yes, still playing Walker, and upgraded to pink Butland and Smalling, because of cost/benefit. It simply hasn't been worth the extra coins to replace these players with others, IMO.
I still don't buy the "handicapping due to squad rating" theory. I've played plenty of games against much higher rated squads where I've gotten crushed, and conversely, have played much lower rated squads where I've done the crushing. I still think much of what we all experience in terms of "handicapping" is based on lag/network latency. Because of lag, animations and collisions are "off" and suddenly your TOTY Ramos is dusted by NIF Musa.