Jason,
15ips 2 track stereo has to be awesome. I have only heard 15 ips 4 track (narrower tracks)
OP has the budget, why not. That's why I mentioned two decks, one 2 track, other 4 track auto-reverse.
I collected around 500 pre-recorded 4 tracks, years ago, they were costing around $8. in those days. I sold about 100 of them on eBay, will sell some more, just need space.
Of the $450. 2 track tapes OP is considering, some content he/you truly like will exist, and then many 4 track tapes that exist of artists/content you really like will never be issued on 2 track format.
I often wonder why more members here (and most audiophiles I know personally) do not have Reel to Reel. If you want great sound, 4 track pre-recorded tapes at 7-1/2 ips will definitely sound better than your/my wonderful Vinyl. (lots of affordable content)
One of the reasons is the content is limited by the era, there is no content for what young people grew up listening to. Yes, they can collect classic rock from our/my era, but not enough incentive to get into tape.
I have some 1/4" 2 track stereo tapes inherited from my uncle (with the Fisher President II, which had the in-line/staggered tape deck in a drawer). They are 7-1/2 ips. They sound even better that the 4 track pre-recorded at the same speed, thus the best source I have.
However, these are all classical, even if I like some classical, those are famous, but not my selections, so I gave my 2 track machine away. I'll probably sell the 2 track tapes.
You can manage to play a 2 track tape on a 4 track deck, just to hear the content. However, not for full fidelity. One track gets picked up ok, and the other track just partial overlap on that track of the head. So you adjust the volume, turn one track down, turn other track up, nothing special sounding about that. But, I can check the tapes before I sell them that way.
Despite what people fear, these tapes are 50, 60, the 2 tracks are 67 years old, and they have strong signal strength, no bleed thru, no shedding, no more s/n than when they were new. Often brittle ends, I put new leaders on both ends.
Of the 500 I bought, I think only 2 were problematic.