The mods on that Z3 are very nicely done and in moderation so that it looks great and is still as reliable as ever. These cars still have FGC characteristics, so they're not completely trouble free, but as far as German cars go, they're on the durable end of the spectrum. The simplicity really helps.
The M-model prices aren't much higher than other Z3s, they look better and have better performance - so it seems to me that looking for one over other Z3 models is a no brainer. Takes patience, is all.
I'd love to back-to-back one with an S2000 - I understand that despite a lot of similarity on the spec sheets, they're VERY different cars in terms of character.
Very interesting comparison for sure. They are very similar in many ways, but also very different in many others. The S2000 is probably a little sharper in handling and reflexes, but it's close. The steering is slightly better in the S2000. The Z3 is slightly smaller but just as comfortable because of the power heated seats, so there a better range of movement. The thing that surprised me the most was how well the transmission, clutch and shift feel in the Z3 compared with the S2K. It's darn near just as good in the Z3, if one less cog. The ratios are different, of course, but both a well suited to thier engines. The Z3M runs around 3500 RPM at 120km/h compared with the Honda's 4000RPM.
The biggest differences is the way you sit inside each, and the power bands. In the Honda you sit lower and in a more inclined position, whereas in the Z3 you are more upright. Both engines pull hard and sound fantastic but the Z3M pulls dead even throughout the power band, where the Honda pulls less well off the line, but then just explodes at ~6000RPM. To be fair though the Z3M is probably putting out about 30HP and 50 toques more than the S2K because its chipped. It's also a little more squirrley in the rear end as well and very easy to induce oversteer. The Z3M is the sonic champ though. It just sounds so good all the time. The S2K sounds ferrocious after the VTEC kicks in but before 4k is just sounds like a regular Honda.
Both are entertaining though, and both look fantastic. Honestly, if I had both in my stable I'd have a hard time deciding which one to take out each time. The most important thing is that they are both playful even with the tc turned on, and both allow you to defeat the tc altogether.