The other strings will still go out of tune when you drop to d unless the trem is set so it can only go down.
When you bend the strings the pitch of the others will change, but the amount depends on the number of springs and tension of the trem.
I have five springs on my strat and you can do double stop country bends no problem
I'd throw in resale value into the decision process on the two guitars as well, it may not seem important now, but might be in future if your tastes change