For my study preparation I have used online racks from Fastlane & IPexpert. This is just simple comparison of these remote rack services.  Here is the hardware comparison of their racks.

Rack Availability:
With IPExpert (or proctorlabs.com) we can book a remote rack minimum for 4 hour slot (effectively 3 hr & 45 min). With Fastlane racks we cannot book it for few hours. You have to book a rack at least for a day or week (effectively 4.5 days).

Therefore flexibility wise IPExpert racks are much better than Fastlane as you can book it when you want it. Since you cannot do labs 24 hrs a day per hour cost of Fastlane racks are much expensive.

Cost:
4 hour slot of rack time is 30$ with IPExpert. You can book 1,5,10,25 slots & you will get discount if you book bulk slots at once. You can check their pricing information from here. You can buy rack time via online payment

Fastlane remote rack is 195$ per day. Their website says they will give 10% discount for consecutive 3 days & 25% for consecutive 5 days. But what I heard was they will use same pods for other wireless classes (like CCNP wireless etc) and no dedicated pods available for CCIE wireless rental purpose (therefor cannot guarantee a rack is available when you need it).  You cannot buy via online payment & sales inquiry responses was very poor.

Remote Support:
During business hours (Monday to Friday US-EST 9:00AM to 5:00PM) IPExpert support staff available to help you via chat. But after hours it will be via email & no staff available at rack locations. So if you suspect a hardware issue no body will be there to check it for you.

In Fastlane, there will be 24×7 remote support and person will be available via skype. So it does not matter which timezone you are working, you will get the same level of support all the time. In that sense fastlane is much better than IPExpert.

Initial Configuration:
In IPExpert remote racks support both  their Volume1 (6 Labs) & Volume2 (5 Labs). You can load initial configuration depend on the labs you want to practice.But you have to sacrifice 15-30 mins to fully load a rack (revert to zero config & then load your lab initial config). Therefore your effective lab time per slot will be around 3 hours if you go with a single slot at a time.

In Fastlane,there is no pre-configuration & you have to build your lab from scratch. No multiple labs available & no option for pre-load configuration. It is pretty much like your home lab.

MSE/ACS/WCS Access:
In fastlane labs these devices SSH access is not available. You have to rely on remote support if you want to check something for you. Due to this you cannot do certain task which you require SSH access.

In IPExpert racks you can do SSH to these devices & you can to almost any task. In that regards IPExpert racks are much better.

CME & VoIP:
This is one area lacking in both racks. There is no way of practicing Voice specific configs by using any of these racks.

In summary I would prefer IPExpert racks over Fastlane & planning to use it for full 8 hr lab (Volume 2 Labs) practices in coming weeks.