Kick drum mic on floor tom?

Depends on the situation and sound I am going for.

If i want something more "metal" with a lot of attack and "SMACK" I go for the D6, if I want something with less attack and more "tone" I go for the SM7.

I have been using the SM7 quite a bit on FT, and even Snare recently. Racks are still 57's or 609's for me.
 
In a pinch, I used a D6 on a floor tom with 3 SM57s on the rack toms. I didn't really like the way they sounded together, but the D6 did provide a great tone. Now that I have D2s and D4s to spare, I've thought about visiting the D6 option again.

Slightly OT: I only have one SM7B and I tend to like it on the high hat. Would it be worth it for me to put it in the kick in the place of a D6 and find another mic for the HH? I blend the D6 with a subkick and sm91.

Actually, blend is a poor choice of words. I rarely, if ever, use the D6 track in the blend. I think I might try it in some pre-tracking samples the next time I'm recording.
 
Anyone use a subkick/speaker for a floor tom's bottom mic around here? I've heard of people doing it or suggesting it, but never actually using it.
 
Anyone use a subkick/speaker for a floor tom's bottom mic around here? I've heard of people doing it or suggesting it, but never actually using it.

To be honest I find most Sub micing to be overkill. You simply don't need that much low end. I built one and it sounds good but I pretty much never use it.
 
I've heard of people just cutting out what they don't need from the signal and just using it for the purpose of picking up the air dispersion. Literally, just getting more KICK from it. With or without the aub-50hz lows.
 
^^^ Very true, however it applies to.... every mic you might use on a tom. Hyper/ supercardioids are safe bets (atm25 and 414's are hypercardioid). 421's (the standard for toms with most engineers) can get a bit more bleed. I find that the drummer's kit setup and your mic placement have the most to do with this. Can't stand when a drummer throws his ride directly over the tom, wonders why you don't want to put your mic right next to it, then complains about his drum sound...

atm25s and 441s (not 414s...that's what you meant, right? Sorry if I'm confused!) are just as susceptible to bleed as 421s; it's all dependent on cymbal position relative to the mic. But pickup pattern isn't really the issue. I think it's more about the voicing of the mic itself. For example, as much as I love that the D6 typically yields a pretty "instant metal" kick sound, for light-footed drummers (all too often a reality when dealing with lots of double-kick work), the D6 in a kick shell will pick up a fair amount of snare bleed, and that snare bleed will sound completely awful due to the mic's voicing. And, since gating the kick won't do you much good in removing the snare bleed in a situation where there's going to be a ton of constant machine gun double kick work, you end up with a pretty ragged snare sound when the kit mics are blended together.

As a side note to your point, in many cases, I actually prefer simple cardioid for rejection, because the rear lobe of hyper- and super-cardioid mics is so sensitive the very frequencies I'm looking to reject (the top end of the cymbals). Placing the tom mics becomes a bit more complex than "point the mic away from the cymbals". Though, to be fair, when considering how the rest of the kit (namely, the snare) will bleed into the tom mics, I suppose that's always going to be a pretty huge consideration.