Hello and welcome, Nick.
I agree with Michael. If look is your main concern, go with vintage pads and a modern module.
Vintage Simmons stuff is flaky and I cross my fingers every time I power up anything with a Simmons logo. While their innovations always led the pack, their designs were occasionally sloppy and prone to failure. If you're good with a soldering iron and multimeter you might really enjoy it. If not, you could end up financing your tech's new pool. Additionally, the manuals are poorly written and use a lot of proprietary lingo making simple concepts confusing. So, there's the 'Why not to buy Simmons stuff.' :)
But, if you really want that classic 'Simmons Sound' the SDSV is the ticket. SDS9 lacks the balls and the bass drum is frustratingly limited. You might also consider SDS7 - similar to SDSV with added digital sound generation, modulation and resonance - or SDS8 - similar to SDSV but only 1 preset. But, again, go this route only if vintage sound generation is a must and samples just won't do.
And, yes, they do make sense as an investment given how their prices have skyrocketed over the last few years. But only if you keep them maintained. See above.
Good luck!