Getting dc's etc has allot less to do with the ISP than your line itself. Thou 384 is not for 25 man really as data can spike to 70k kb+/sec for brief periods (seconds) but its generally less than 10kb/s. Its in those seconds that you see the problems on slower lines also.
I raid on Web Africa standard acct with a proxy and have 200-220ms stable in 25 mans.
I can also raid on my IS based uncapped account with a 300-380ms latency.
BUT the difference is the WA acct is very very stable. It stays @ that latency where other ISP (I've used many different ones) might give you a good overall latency, it spikes allot more. Something you will clearly realize if you play a caster class.
The biggest issue ppl have with lag and DC's has to do with their line quality itself. It has proven itself to me over and over. I have moved 4 times in the last couple of years and every time the line quality obviously changes and so does my wow problems with that. For me SNR or Noise Margin has gone hand in hand with WOW lag and DC's.
My new house have a great quality line, compaired to my previous house which had an ok line, but it was prone to getting a Noise Margin that jumps around. Having a stable NM, even if its on the low side is ok (ideally for wow u want 12+, but 10+ will do if its stable), but when it starts moving all the time, specially below 10 you get problems.
When my Noise Margin goes low and there allot happening in game I used to get problems. I can even pickup the phone and hear the noise on the line. Then you know its really bad.
My current line quality looks something like below. Thats great and I have not had 1 single problem for 3 months and I raid decently serious 25 man (8/13HC)
ADSL Link Downstream Upstream
Connection Speed 4096 kbps 512 kbps
Line Attenuation 18.0 db 9.0 db
Noise Margin 28.6 db 14.0 db
Anyway, thats my opinion and personal experience on things.