I only stand on my rollers to rest my butt. It's odd to me to dis rollers for not being good for max standing efforts. As if trainers were? Both are worthless for max efforts because you're not accelerating your mass. The feel of OOS efforts on trainers or rollers is completely different from on the road because you aren't accelerating your mass up the road and then reaching terminal velocity. Plus on the usual trainer you can't rock the bike which is so important to sprinting performance. The place to train sprinting is on the track or outdoors.

OTOH I can certainly do max seated efforts on my rollers except that the acceleration has a completely different feel, as above. Z5 intervals are also a little different on my 500 watt set because even in top gear my cadence will be a little higher than what I would use for Z5 climbing intervals on the road. The 800+ watt Sportscrafters set would be better in that respect.