yellowfish:
The hydros does not come with any pockets, but you can buy and attach two pockets to it. SP makes two sizes of pockets, a "ninja" pocket and a larger pocket. As with any BC, you can also thread an accessory pocket on to the waist belt if you want to. The Lotus has the one pocket but you could add another if you needed. A lot things you might think need a pocket can also be clipped to a BC.
I think the SP weight pockets are more secure that the Aqualung, but that said, neither my wife nor I have ever had an AL pocket fall out. They need to be firmly "clicked" into place, but then they stay. I have read posts where people have talked about the pockets falling out, but I suspect these were user error. If the BC otherwise suits you, I would not worry about it too much. If it is a major concern, then yes, the design of the SP is more secure...unless you don't latch it right, in which case the weights can fall out. Either BC should be fine if used properly and the weight pocket designs on each have been used for years by the respective companies. You also need to not exceed the rated weight for a given weight pocket.
Rental BCs are typically low-end models, often not well fitted to you and sometimes quite well-worn. It is hard to compare them to anything. You won't find many ops renting high end scubapro or aqualung BCs.
A back inflate generally only causes any "pushing" issues at the surface if you are over weighted and/or the BC over-inflated. I am sure they are less "comfortable" at the surface than the wrap around type, but I am more concerned how they perform on the dive. I think sometimes when you read about the pushing forward issue, it is because some people try to use the BC like like a fishing float tube and get much of their torso out of the water on the surface. That doesn't work so well.
I like the I3 and have never had any problem with it getting caught on anything. It is the subject of a few "you are going to die" posts here on SB, but that is true of anything new. Really, the lever only protrudes about an inch, if that much. If it were to be accidentally activated on the boat it would not be much of an issue anyway. Un-snag it and inflate or deflate. The advantages to the i3 is that it is better at deflating the BC in a variety of positions while diving, unclutters your front , and frankly, if you had to disconnect the inflator hose, I think it would be easier. I like it because I usually have this huge dive camera housing tethered to my shoulder D ring, and less "stuff" hanging off my chest is nice. AL claims some other benefits and you can look at what they say. You can also get the Lotus without the i3 if it is a concern. I think that understanding how to respond to an equipment failure while remaining calm, and regardless of the particular equipment used, is the key to safety. With the i3 it may, however, be more important to have the BC serviced annually than it would other types.
Comfort should best be judged in a wetsuit (assuming you usually use one) and with a tank on. Preferably with the opportunity to get in a pool and move around and get in different positions. The Lotus will be more comfortable on land when loaded. If you do a lot of shore diving with decent walks to the water, that could be important, especially if you have any strength, age or medical issues.
Try hard to get a chance to dive them both in a pool. Make sure you get the right size. Some shops want to sell what is in stock, and may not be quite as, um, forthright (?) on sizing as they should be.
These might help a bit:
BC Aqua Lung Lotus i3
Scubapro Hydros Pro BCD - Gear Review | Diving Adelaide
REVIEW: SCUBAPRO HYDROS PRO - DIVE Magazine
Product Review: Aqualung Lotus i3 BCD