VX Partner Award Availability on VS

I'm trying to get a handle on how much availability partner award space there tends to be on the US-LON flights for UC tickets. I checked with the Delta booking engine (it's the best choice I have for checking non-VS award options) as well as with VS's website, and what I generally get is the following:
-Very thin availability SFO-LON (20 days in the first six months of 2015 per VS's website)
-Very thin availability MCO-LON (11 days in the first six months of 2015 per VS's website, 9 of which are in late June and which probably coincide with VS running a larger fleet to/from MCO)
-Moderate availability IAD-LON (39 days in the first six months of 2015 per VS's website, with a modest bias towards the winter/spring)
-Similar availability BOS-LON (38 days in the first six months of 2015 per VS's website)
-Extreme availability NYC-LON (19 days in January alone per VS's website, and 20-21 days available per DL's website...though DL's was a mild pain to use and it is plausible that I counted a day twice or that some availability changed; 21 days of 28 in Feb per VS's website, 29/31 in Mar, 27/30 in Apr, 26/31 in May, and 28/30 in Jun for about 150/181 days of availability...as well as substantial availability in December (including spaces on 5 of 6 flights for today as of about midnight, and space through 12-16 and 12-23 to 12-31 per DL).

Does all of this sound about right and/or does VX have significantly less access than DL?

THats actually better than most years.

Availability is good at the moment. Usually its a bit less than that. Im impressed you found 11 days from MCO though. Those are extremely rare.

Not sure how it maps to VX but trying to redeem VS miles on DL I found that the availability was different (read "less") than what was shown on the DL website. It took a phone call to flying club to find out what was open to book with flying club miles.

It can also change back and forth quite a bit on the longer US routes, SFO and LAX. LAX got a whole lot harder this winter from what I can see with VS going down to one flight. I'm on a VX challenge to Gold and a couple of weeks ago a G popped up for SFO-LHR so booked a PE S and upgraded (had some miles left from way back when). I was coming back into NYC, that was no prob at all. I did see a lot of variability on the SFO route from week to week.