Hey, nice email. I am going to make an admission up front- I am not a tube junkie, especially pre-amp tubes. I live in Petaluma, and have a professional and personal relationship with the guys at Mesa. They tend to keep me in tubes, and I run stock Mesa pre-amp and rectifier tubes. I do play around with power tubes though.
Again, my HB is modded, so my tones and gain are much different than yours. I can get some decent clip/sizzle in Love low gain but that isn't where I live. I either use Love for fender/high headroom cleans or on the hi-gain Mk1 setting. My amp absolutely nails Mk 1 tones. I use Lust low-gain to get a more Vox-y chimey british clip overdrive, as this particular mod really shines there.
As to the two cabs- I picked up the Recto 2x12 specifically for this amp, hoping to get a tighter attack and more present, in your face, feel. It definitely delivered there and I was totally digging the tones, even though I am not usually a V30 lover. This cab was recommended to me by a good friend/Mesa Artist/studio engineer, who also doesn't usually use V30's but feels this particular cab sounds really good. So, the Recto definitely could help you with more mid focus, tighter attack and cutting through the mix. I just picked up the old vert halfback 2x12 (MC90 on top, EVM12L on bottom) for a song, as I have the matching 4x12 version for my Mk V and wanted something a little smaller. I immediately noticed how much more musical and rich it was compared to the Recto. While not as tight, the low end is more balanced, richer, and thumpier. It seems more 3-dimensional and sonically more complex than the Recto. It is more pleasant to my ears, even though I was digging the Recto. If I were using it in a rock situation, and needed to cut through a mix with a second guitarist, I'd go with the Recto. If I was using it in a more open, loose perhaps jazzy or fusion type setting, or where I wasn't constantly competing with another guitar of keyboards for sonic space, I'd go with the halfback, as the tone is more soulful and balanced.
Now, I can update this when my Royal Atlantic arrives......... and which will force me to sell the HB! If you know anyone who might want an awesome HB head, modded by our very own Andy/ Monsta-Tone, throw them my way.
Brent