Just to clarify, if I go Pulse8 it's TT (I assume TalkTalk) Wholesale, but IDNet it's BTWholesale?
Pulse 8 is Talk Talk Wholesale and is Metal Path Facility connection where the broadband and phone services are bound together.
As far as i know IDNet still use TTw, BTw and Zen for their backhaul connections. At one stage the default was Zen, but I've no idea whether that is still the case or indeed whether they are still using Zen. The main difference is that it is a Shared Metal Path Facility connection, so your phone line can be on BTw, but your broadband on TTw or Zen. This does make migration away much easier so a definite plus for IDNet.
IDNet support has been brilliant for me, as they have swapped me from TTw to Zen and finally to BTw to resolve inconsistent single thread speeds; Pulse8 struggled to get TTw's attention when I had significant single thread speed problems with them, but did eventually get it sorted thanks to Adam mithering them. My BTw connection has been absolutely rock solid for the last 2.5 years with teh single thread and multi thread speeds matching on the TBB speed test.
If you pay for an annual contract you pay get one month free, however you do have to pay it all up front. This is what I am doing and I am only paying ~£4 more a month than I would with Pulse8.
I think the difference is worth it, but YMMV.
One other choice you might want to consider is going to TT Business who are offering some very favourable deals at the moment. The downside is that you are taking out a 24 month contract with TTB, whereas Pulse8 and IDNet are 1 month rolling contracts. Not sure I can bring myself to commit for that length of time, but there are significant savings to be had, so worth a think.