You can find many spirited debates on the WildBlue forum sites, and WB has changed how they require the dish to be grounded, but I don't believe it makes a spec of difference for speed/performance. It is required for installation, however, and if you don't have a grounded system, it is an indicator of the level of professionalism of your installer. Often a missing ground, is a warning flag that your installer does not pay attention to details. What else did he/she skimp on?
Assuming your computer and/or router aren't a bottleneck, speed/performance is primarily a function of dish pointing (it's really pretty particular) and beam loading. Talk to other people in your coverage beam and compare speeds for the same sites at the same time of day.
I am in beam 37 on the Anik F2 satellite and get my "up to rate" probably 90% of the time. I do notice a crunch a couple of weeks before Christmas with all of the on line shoppers, but that could be the sites I vist.
as a hns tech for years, id strongly disagree with you guys based on comparison of the two systems only. with hns systems, if you DONT ground you WILL have problems guaranteed. i know we had a debate over this last year...so here we go again. your transmitter just through the natural process of working, will create static. if that static has nowhere to escape (a proper ground), it WILL cause problems, whether it be shorting out the transmitter, modem, or the line itself. its just a matter of time and usage as to when the "problem" of no ground becomes an issue. i still come across installs from newbies who dont think grounding is important, and guess what, a blown transmitter needs to be replaced. so in my opinion, NOT KNOWING ANYTHING TO IMPORTANT ABOUT WB, i would have to say that, yes, grounding will make a difference.
oops reread post, it will affect what the cx believes is slow speeds based on failing transmissions. if your transmitter do to lack of ground, has to keep resending packets, and resending packets, and resending packets............its going to take a little longer for the complete message to be transmitted. once received, your download will be fine. so a non grounded system will slowly lose upload speeds, whereas download speeds from what ive seen, are usually unaffected. overall system performance becomes degraded overtime.