I have 2 months of solid use with the Ys-D1 in the Indo Pacific, Just returned a few weeks ago. and am now shooting with them in California.
I always travel with multiple sets of strobes and was very doubtful of the performance of the D1. Being a diehard 250 user i didnt think i would be happy with the D1 but took an open minded approach to using them.
I have to say, i am pretty happy overall and i will list the reasons
For travel-compact and lighter
output-great dump recovery but a bit slow (compared to the 250) on full dumps
Great kelvin color-Even with extreme ambient light the strobes worked well
Sunballs and high F-stops-No problem
Downfall-on/off switch can be moved easily when making adjustments
finesse - setting are rather generic vs. the 250 which offers alot of finesse from drop of directed light to x-rays..
I shoot alot in the Indo-Pacific probably 6 months or more a year, and i mean every day, so strong output and quick recovery are extremely important to me. This is the only drawback to the D1 strobe, however i meet that challenge with Eneloop or Belkin batteries and so far im okay with the performance.
I used to use the YS110a for macro and the 250pro for wide angle. On this last trip i never powered up the 250's once...
Overall Value-excellent
performance-great +
ease of travel-Excellent
Hope this helped...and good luck..
Oh and one other thing...and this s not a plug..I purchased my strobes through Bluewater photo and they were very helpful...