Hi Tom,
Fair question, and my answer would be no, but only because there seemed to be some perf damage on the bottom (even though it was listed as no faults), otherwise it was a beautiful stamp that would have been a welcomed addition to my collection. I don't really purchase "investment" stamps, I tend to only look for a single high quality, attractive specimen of each stamp for my collection but I'm patient and look for great deals. In all honesty, since restarting this hobby, I have yet to buy anything with the intention of trying to sell it for an ROI. Not oging ot say I wouldn't do this later down the road as a way to fund additional purchases, but I barely have enough time to build my meagre collection, let alone try and make a small business out of it :)
*EDIT - I re-read what I wrote and now I'm wondering if you meant "investment stamp" as in a super high quality stamp to keep long term, or a stamp I would try to purchase at a low price and resell immediately for a profit. If you meant a long term high quality stamp, I will always try for VFMNH if it's in my budget. Once a stamp's VFMNH selling price is over $500, my wallet starts puckering up ;) And even at that price range, I would only splurge like that once every few months.
Here's the stamp in question:

I'll just sit back and wait, another striking #38 at a good price is bound to come up again :) An MH-VF wouldn't be unrealistic, a VFMNH would, on the other hand, be too expensive - I see CV on that is at $3772.05 so purchase price is probably around $850 or higher.
Take care,
Dan