EMB ERJ 190/195 ER/LR
Flight Crew Air Transport Pilot (ATP)
Confusion
No Specific Anomaly Occurred All Types
Flight Crew Became Reoriented
Chart Or Publication; Human Factors
Our flight had no problems; but we can see a real possiblity of issues with new Climb Via SID's relating to the Houston RNAV departures. I had heard from another pilot that they had an issue; so we were ready for the inconsistency. Called him after our flight and found out he had not filed an event report or ASRS.  We had a 'climb via' on the GUMBY1 Departure from IAH. It has a 5;000 foot level off and then says to maintain 4;000. (My First Officer missed this on his departure preparation; but I had heard about it previously.) On the 'Climb Via' departures the crews are not supposed to give the altitude they are climbing to... Quite a chance for confusion and altitude busts in a congested terminal airspace!No event; but very high chance of confusion and possibly a major incident/accident.  The problem is the confusing RNAV departure plates for Houston - which includes the GUMBY1; but also the MMALT1; the MMUGS1; and the RITAA1 from what I could see. Rewrite the RNAV departures out of IAH to get rid of the cleared altitude inconsistencies.  And rethink the 'Climb Via' changes; especially in these terminal areas where they don't really save any time and can be confusing.  When the crews just say 'climbing via the XXX SID' we are giving up a valuable barrier to miscommunication on altitude assignments. And the average pilot (and many controllers) seem to be finding the ensueing modifications on altitudes and speeds confusing.
EMB-190 Captain believes the new RNAV departures out of IAH are an accident waiting to happen; due to the 4;000 foot altitude restriction hidden in the routing box.