I own two Heartfield basses: a Cherry Burst (?) DR-6C (neck-thru) 6 string and a Black Pearl Burst DR-5 bolt-on 5 string. Granted the single knob and switch may not give a player a wide range of tones I still like my Heartfields very much. I am a sucker for a bass with a good feeling/playing neck and both of my basses have very comfortable (for me) wide necks. I can't think of many other basses that I have tried (boutique or factory made) that feel as good as my DR-5 5 string. I wouldn't sell or trade it for anything.
The 5 string models have 19 millimeter string spacing at the bridge which is wide, but it suits me fine. The 6 string models have 17.5 millimeter string spacing at the bridge. I only wish the 6 string models had 19 millimeter spacing and a slightly wider neck. I personally perfer the tone of the bolt-on model; it is brighter and snappier than the neck-thru bass in my opinion.
I do have an issue with the trust rod in my 6 string. It is frozen in place currently. I don't know of any bass luthier/repair men that I trust to fix it. At least not where I live.
As stated above the tone of Heartfield basses may not be the greatest, but I still love mine.
I've had my 5 string since 1992 and my 6 string since mid 1994. I only wish I had had the money (at the time) to buy a DR-4 four string a another DR-5 string in the red pearl burst finish.