I've shot more recent production 4006TSW's than the older 4006's.
I think they're a pretty decent full-size pistol for the caliber.
Heavy, though. I actually liked the 4003TSW when I was doing some shooting with a T&E gun. Certainly lighter than the all-steel model, which would be appreciated after wearing one all day/night. The heavier all-steel gun would probably be found to help with the .40's felt recoil by many folks, though. Just depends.
FWIW, I was told that when the CHP out this way (CA) were considering replacing their aging inventory of hard-used 20-year old 4006's, their own initial testing found that the TSW versions would probably be more durable, and last longer, than their older 4006's. Not surprising, considering the design and manufacturing improvements that have occurred over the years and the tighter tolerances incorporated in the TSW's. Their officers tend to do a lot of training/practice shooting, as an agency, though.
Last I heard, the company wasn't making any more barrels for the 4006's, and the TSW barrels have some dimensional differences (thicker barrel hoods, for one thing).
A friend of mine who retired from the CHP told me that the agency had offered to let each officer buy their 4006, if they desired (meaning they could buy ONE 4006

). I can't remember the price he related, but it was pretty low ($135 or $235??).
Dunno. Wasn't interested at the time ... and he owned an older 4013, so he wasn't interested in buying his former 4006 duty weapon, either. (Reminds me of the time I was called by the armorer for an agency transitioning from Beretta 92's to 96's, and the guy told me he could set aside an unissued Beretta 92 that I could buy through a local dealer for something like $216, but I passed because I just didn't like the model enough to pay that for one.)
If I were to pick up a used 4006, the first thing I'd do would be to replace the recoil & mag springs, and the followers if they weren't the current light blue ones.
I knew an armorer for a local agency who had to let their 4006's run beyond the factory recommended 5 year (or 5K rounds fired) spring replacement interval (not his choice). During qualifications at the 7 year point he said they started seeing a sudden occurrence of feeding problems that were attributable to weakened springs. He got the money for new springs.

Just something to think about.