Crosman 1377c or 2289g? Advantages? Disadvantages?

I am thinking of getting either a Crosman 1377c or 2289g. I figure it will compliment the eventual purchase of a RWS 350 when I take the plunge into something more serious. I like the fact that the Crosman's are inexepnsive and require no inputs - other than a bit of effort to pump them. The easy modding is also a bonus. So my decision for a first step into the world of airgunning is basically between these two guns.

I will be buying the Canadian versions, so both are de-tuned to an advertized 485 fps. Since the 1377 is .177 and the 2289 uses .22 pellets, will the de-tuned 2289 have more hitting power? It seems like it should if it shoots a heavier pellet just as fast, but I am curious if anyone has any real world experience. My concern is that they hve the same de-tuned power plant, so the 2289 will be slower despite the advertised velocities. Ideally, it would be 'de-tuned less' to allow the .22 pellet to hit the same top speed.

Also, are there any advantages to converting a 1377 to a .22 calibre versus just buying the 2289? It seems like the .22 cal conversion is one of the more common mods to a 1377, so I think I will just be avoiding those specific mods if I go with the 2289 right out of the gate. Are there any downsides to this?

If they use similar power plants, are their significant differences between the potential speeds they can attain with the appropriate mods? Thus, if I eventually install the flat-top piston, plug th bleed valve, etc., will the 1377 eventually have more velocity due to the limits of the power plant and the heavier pellets of the 2289?

My previous questions/research was about springers (thus the plan to get a RWS 350 eventually - what a beauty), so I don't know as much about multi-pumps. A couple of more general questions:

- Can you leave them pumped up for a while without damaging the internals? (not like 2 years, but for an hour or two while you are wandering around).

- Are they durable? Life expectancy? mantenance?

I figure at $80 I can't really go too far wrong, and even when i upgrade this will still be a great backpacker. Any help/info you guys want to pass on (including any useful info I haven't asked about) would be great. I got some great answers to my previous questions - they were much appreciated.